Messages

Create a Message

POST /v1/messages

Send a structured list of input messages with text and/or image content, and the model will generate the next message in the conversation.

The Messages API can be used for either single queries or stateless multi-turn conversations.

Learn more about the Messages API in our user guide

Headers

• "anthropic-beta": optional array of AnthropicBeta

  Optional header to specify the beta version(s) you want to use.

  • string

  • "message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 42 more

    • "message-batches-2024-09-24"

    • "prompt-caching-2024-07-31"

    • "computer-use-2024-10-22"

    • "computer-use-2025-01-24"

    • "pdfs-2024-09-25"

    • "token-counting-2024-11-01"

    • "token-efficient-tools-2025-02-19"

    • "output-128k-2025-02-19"

    • "files-api-2025-04-14"

    • "mcp-client-2025-04-04"

    • "mcp-client-2025-11-20"

    • "dev-full-thinking-2025-05-14"

    • "interleaved-thinking-2025-05-14"

    • "code-execution-2025-05-22"

    • "extended-cache-ttl-2025-04-11"

    • "context-1m-2025-08-07"

    • "context-management-2025-06-27"

    • "model-context-window-exceeded-2025-08-26"

    • "skills-2025-10-02"

    • "fast-mode-2026-02-01"

    • "output-300k-2026-03-24"

    • "user-profiles-2026-03-24"

    • "user-profiles-2026-08-18"

    • "user-profiles-2026-09-04"

    • "advisor-tool-2026-03-01"

    • "managed-agents-2026-04-01"

    • "cache-diagnosis-2026-04-07"

    • "dreaming-2026-04-21"

    • "thinking-token-count-2026-05-13"

    • "server-side-fallback-2026-06-01"

    • "server-side-fallback-2026-07-01"

    • "fallback-credit-2026-06-01"

    • "fallback-credit-2026-07-01"

    • "agent-memory-2026-07-22"

    • "mid-conversation-tool-changes-2026-07-01"

    • "compact-2026-01-12"

    • "computer-use-2025-11-24"

    • "mcp-tunnels-2026-06-22"

    • "structured-outputs-2025-11-13"

    • "task-budgets-2026-03-13"

    • "thinking-display-updates-2026-08-18"

    • "ce-user-management-2026-07-13"

    • "mid-conversation-output-config-2026-07-01"

    • "thinking-binding-controls-2026-08-01"

    • "mid-conversation-system-clear-at-2026-08-21"

• "anthropic-user-profile-id": optional string

  The user profile ID to attribute this request to. Use when acting on behalf of a party other than your organization. Requires the user-profiles beta header.

• "anthropic-workspace-id": optional string

Body parameters

• max_tokens: number

  The maximum number of tokens to generate before stopping.

  Note that our models may stop before reaching this maximum. This parameter only specifies the absolute maximum number of tokens to generate.

  Set to 0 to populate the prompt cache without generating a response.

  Different models have different maximum values for this parameter. See models for details.

  minimum: 0

• messages: array of BetaMessageParam

  Input messages.

  Our models are trained to operate on alternating user and assistant conversational turns. When creating a new Message, you specify the prior conversational turns with the messages parameter, and the model then generates the next Message in the conversation. Consecutive user or assistant turns in your request will be combined into a single turn.

  Each input message must be an object with a role and content. You can specify a single user-role message, or you can include multiple user and assistant messages.

  If the final message uses the assistant role, the response content will continue immediately from the content in that message. This can be used to constrain part of the model's response.

  Example with a single user message:

  [{"role": "user", "content": "Hello, Claude"}]

  Example with multiple conversational turns:

  [
    {"role": "user", "content": "Hello there."},
    {"role": "assistant", "content": "Hi, I'm Claude. How can I help you?"},
    {"role": "user", "content": "Can you explain LLMs in plain English?"},
  ]

  Example with a partially-filled response from Claude:

  [
    {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
    {"role": "assistant", "content": "The best answer is ("},
  ]

  Each input message content may be either a single string or an array of content blocks, where each block has a specific type. Using a string for content is shorthand for an array of one content block of type "text". The following input messages are equivalent:

  {"role": "user", "content": "Hello, Claude"}

  {"role": "user", "content": [{"type": "text", "text": "Hello, Claude"}]}

  See input examples.

  Note that if you want to include a system prompt, you can use the top-level system parameter — there is no "system" role for input messages in the Messages API.

  There is a limit of 100,000 messages in a single request.

  • content: string or array of BetaContentBlockParam

    • string

    • array of BetaContentBlockParam

      • BetaTextBlockParam object

        • type: "text"

        • text: string

          minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

          • type: "ephemeral"

          • ttl: optional "5m" or "1h"

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            • 5m: 5 minutes
            • 1h: 1 hour

            Defaults to 5m. See prompt caching pricing for details.

            • "5m"

            • "1h"

        • citations: optional array of BetaTextCitationParam or null

          • BetaCitationCharLocationParam object

            • type: "char_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_char_index: number

            • start_char_index: number

              minimum: 0

          • BetaCitationPageLocationParam object

            • type: "page_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_page_number: number

            • start_page_number: number

              minimum: 1

          • BetaCitationContentBlockLocationParam object

            • type: "content_block_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

          • BetaCitationWebSearchResultLocationParam object

            • type: "web_search_result_location"

            • cited_text: string

            • encrypted_index: string

            • title: string or null

              maxLength: 512, minLength: 1

            • url: string

              minLength: 1

          • BetaCitationSearchResultLocationParam object

            • type: "search_result_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • search_result_index: number

              0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from document_index; server-side web search results are not included in this count.

              minimum: 0

            • source: string

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

            • title: string or null

      • BetaImageBlockParam object

        • type: "image"

        • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

          • BetaBase64ImageSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

              • "image/jpeg"

              • "image/png"

              • "image/gif"

              • "image/webp"

          • BetaURLImageSource object

            • type: "url"

            • url: string

          • BetaFileImageSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • transformations: optional BetaImageTransformationsParam or null

          Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

          • oversized_image: optional "downsize" or "error"

            What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

            • "downsize"

            • "error"

      • BetaRequestDocumentBlock object

        • type: "document"

        • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

          • BetaBase64PDFSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "application/pdf"

          • BetaPlainTextSource object

            • type: "text"

            • data: string

            • media_type: "text/plain"

          • BetaContentBlockSource object

            • type: "content"

            • content: string or array of BetaContentBlockSourceContent

              • string

              • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

                • BetaTextBlockParam object

                • BetaImageBlockParam object

          • BetaURLPDFSource object

            • type: "url"

            • url: string

          • BetaFileDocumentSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

          • enabled: optional boolean

        • context: optional string or null

          minLength: 1

        • title: optional string or null

          maxLength: 500, minLength: 1

      • BetaSearchResultBlockParam object

        • type: "search_result"

        • content: array of BetaTextBlockParam

          • type: "text"

          • text: string

            minLength: 1

          • cache_control: optional BetaCacheControlEphemeral or null

            Create a cache control breakpoint at this content block.

          • citations: optional array of BetaTextCitationParam or null

        • source: string

        • title: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam

      • BetaThinkingBlockParam object

        • type: "thinking"

        • signature: string

          The signature value of this thinking block, exactly as returned by the API in a previous response. Used to verify that the block was generated by Claude.

          Thinking blocks must be passed back unmodified and in their original order; a modified block results in a 400 invalid_request_error.

        • thinking: string

          The thinking text of this block as returned by the API.

      • BetaRedactedThinkingBlockParam object

        • type: "redacted_thinking"

        • data: string

          The data value of this redacted thinking block, exactly as returned by the API in a previous response. Opaque and encrypted; pass it back unchanged.

      • BetaToolUseBlockParam object

        • type: "tool_use"

        • id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • input: map[unknown]

        • name: string

          maxLength: 200, minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

            • type: "direct"

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

            • type: "code_execution_20250825"

            • tool_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

          • BetaServerToolCaller20260120 object

            • type: "code_execution_20260120"

            • tool_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • toolset_name: optional string or null

          For a toolset member tool_use, the toolset family this member belongs to.

          maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

      • BetaToolResultBlockParam object

        • type: "tool_result"

        • tool_use_id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

          • string

          • array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

            • BetaTextBlockParam object

            • BetaImageBlockParam object

            • BetaSearchResultBlockParam object

            • BetaRequestDocumentBlock object

            • BetaToolReferenceBlockParam object

              Tool reference block that can be included in tool_result content.

              • type: "tool_reference"

              • tool_name: string

                maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

            • BetaBrowserStateBlockParam object

              The caller's browser state after a browser toolset member call — the full inventory of open tabs, which tab is active, and any side effects (tabs opened, download state changes) the call produced.

              At most one per tool_result, only on a non-error result answering a browser toolset member tool_use. The server renders the model-visible text from it; the model never sees the raw fields.

              • type: "browser_state"

              • tabs: array of BetaBrowserStateTabEntry

                All tabs open in the browser after this call — the full inventory, not a delta. May be empty. Whenever non-empty, exactly one entry carries active: true.

                maxItems: 100

                • tab_id: string

                  The caller-assigned identifier for this tab, unique within the inventory.

                  maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • title: string

                  The title of the page the tab is showing. May be empty.

                  maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • url: string

                  The URL of the page the tab is showing. May be empty.

                  maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • active: optional boolean

                  Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

              • state_changes: optional array of BetaBrowserStateChange or null

                Tabs opened and download state changes during this call. "Nothing to report" is expressed by omitting the field, never by an empty list.

                maxItems: 200, minItems: 1

                • BetaBrowserStateChangeTabOpened object

                  A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

                  Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

                  • type: "tab_opened"

                  • tab_id: string

                    The tab_id of the opened tab, present in tabs.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • BetaBrowserStateChangeDownloadStarted object

                  A file download that started during this call.

                  • type: "download_started"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • BetaBrowserStateChangeDownloadCompleted object

                  A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

                  • type: "download_completed"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • path: optional string or null

                    Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

                    pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

                  • size_bytes: optional number or null

                    The completed download's size.

                    minimum: 0

                • BetaBrowserStateChangeDownloadFailed object

                  A file download that failed — or was cancelled — during this call.

                  • type: "download_failed"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • error: optional string or null

                    The failure or cancellation detail, when known.

                    pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

        • is_error: optional boolean

        • toolset_name: optional string or null

          For a toolset member tool_result, the toolset family of the paired tool_use.

          maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

      • BetaServerToolUseBlockParam object

        • type: "server_tool_use"

        • id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • input: map[unknown]

        • name: "advisor" or "web_search" or "web_fetch" or 5 more

          • "advisor"

          • "web_search"

          • "web_fetch"

          • "code_execution"

          • "bash_code_execution"

          • "text_editor_code_execution"

          • "tool_search_tool_regex"

          • "tool_search_tool_bm25"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaWebSearchToolResultBlockParam object

        • type: "web_search_tool_result"

        • content: BetaWebSearchToolResultBlockParamContent

          • ResultBlock = array of BetaWebSearchResultBlockParam

            • type: "web_search_result"

            • encrypted_content: string

            • title: string

            • url: string

            • page_age: optional string or null

          • BetaWebSearchToolRequestError object

            • type: "web_search_tool_result_error"

            • error_code: BetaWebSearchToolResultErrorCode

              • "invalid_tool_input"

              • "unavailable"

              • "max_uses_exceeded"

              • "too_many_requests"

              • "query_too_long"

              • "request_too_large"

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaWebFetchToolResultBlockParam object

        • type: "web_fetch_tool_result"

        • content: BetaWebFetchToolResultErrorBlockParam or BetaWebFetchBlockParam

          • BetaWebFetchToolResultErrorBlockParam object

            • type: "web_fetch_tool_result_error"

            • error_code: BetaWebFetchToolResultErrorCode

              • "invalid_tool_input"

              • "url_too_long"

              • "url_not_allowed"

              • "url_not_in_prior_context"

              • "url_not_accessible"

              • "unsupported_content_type"

              • "too_many_requests"

              • "max_uses_exceeded"

              • "unavailable"

              • "content_too_large"

          • BetaWebFetchBlockParam object

            • type: "web_fetch_result"

            • content: BetaRequestDocumentBlock

            • url: string

              Fetched content URL

            • retrieved_at: optional string or null

              ISO 8601 timestamp when the content was retrieved

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaAdvisorToolResultBlockParam object

        • type: "advisor_tool_result"

        • content: BetaAdvisorToolResultErrorParam or BetaAdvisorResultBlockParam or BetaAdvisorRedactedResultBlockParam

          • BetaAdvisorToolResultErrorParam object

            • type: "advisor_tool_result_error"

            • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

              • "max_uses_exceeded"

              • "prompt_too_long"

              • "too_many_requests"

              • "overloaded"

              • "unavailable"

              • "execution_time_exceeded"

              • "model_not_found"

          • BetaAdvisorResultBlockParam object

            • type: "advisor_result"

            • text: string

            • stop_reason: optional string or null

          • BetaAdvisorRedactedResultBlockParam object

            • type: "advisor_redacted_result"

            • encrypted_content: string

              Opaque blob produced by a prior response; must be round-tripped verbatim.

            • stop_reason: optional string or null

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaCodeExecutionToolResultBlockParam object

        • type: "code_execution_tool_result"

        • content: BetaCodeExecutionToolResultBlockParamContent

          Code execution result with encrypted stdout for PFC + web_search results.

          • BetaCodeExecutionToolResultErrorParam object

            • type: "code_execution_tool_result_error"

            • error_code: BetaCodeExecutionToolResultErrorCode

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

          • BetaCodeExecutionResultBlockParam object

            • type: "code_execution_result"

            • content: array of BetaCodeExecutionOutputBlockParam

              • type: "code_execution_output"

              • file_id: string

            • return_code: number

            • stderr: string

            • stdout: string

          • BetaEncryptedCodeExecutionResultBlockParam object

            Code execution result with encrypted stdout for PFC + web_search results.

            • type: "encrypted_code_execution_result"

            • content: array of BetaCodeExecutionOutputBlockParam

              • type: "code_execution_output"

              • file_id: string

            • encrypted_stdout: string

            • return_code: number

            • stderr: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaBashCodeExecutionToolResultBlockParam object

        • type: "bash_code_execution_tool_result"

        • content: BetaBashCodeExecutionToolResultErrorParam or BetaBashCodeExecutionResultBlockParam

          • BetaBashCodeExecutionToolResultErrorParam object

            • type: "bash_code_execution_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

              • "output_file_too_large"

          • BetaBashCodeExecutionResultBlockParam object

            • type: "bash_code_execution_result"

            • content: array of BetaBashCodeExecutionOutputBlockParam

              • type: "bash_code_execution_output"

              • file_id: string

            • return_code: number

            • stderr: string

            • stdout: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaTextEditorCodeExecutionToolResultBlockParam object

        • type: "text_editor_code_execution_tool_result"

        • content: BetaTextEditorCodeExecutionToolResultErrorParam or BetaTextEditorCodeExecutionViewResultBlockParam or BetaTextEditorCodeExecutionCreateResultBlockParam or BetaTextEditorCodeExecutionStrReplaceResultBlockParam

          • BetaTextEditorCodeExecutionToolResultErrorParam object

            • type: "text_editor_code_execution_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

              • "file_not_found"

            • error_message: optional string or null

          • BetaTextEditorCodeExecutionViewResultBlockParam object

            • type: "text_editor_code_execution_view_result"

            • content: string

            • file_type: "text" or "image" or "pdf"

              • "text"

              • "image"

              • "pdf"

            • num_lines: optional number or null

            • start_line: optional number or null

            • total_lines: optional number or null

          • BetaTextEditorCodeExecutionCreateResultBlockParam object

            • type: "text_editor_code_execution_create_result"

            • is_file_update: boolean

          • BetaTextEditorCodeExecutionStrReplaceResultBlockParam object

            • type: "text_editor_code_execution_str_replace_result"

            • lines: optional array of string or null

            • new_lines: optional number or null

            • new_start: optional number or null

            • old_lines: optional number or null

            • old_start: optional number or null

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaToolSearchToolResultBlockParam object

        • type: "tool_search_tool_result"

        • content: BetaToolSearchToolResultErrorParam or BetaToolSearchToolSearchResultBlockParam

          • BetaToolSearchToolResultErrorParam object

            • type: "tool_search_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

            • error_message: optional string or null

          • BetaToolSearchToolSearchResultBlockParam object

            • type: "tool_search_tool_search_result"

            • tool_references: array of BetaToolReferenceBlockParam

              • type: "tool_reference"

              • tool_name: string

                maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaMCPToolUseBlockParam object

        • type: "mcp_tool_use"

        • id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • input: map[unknown]

        • name: string

        • server_name: string

          The name of the MCP server

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaRequestMCPToolResultBlockParam object

        • type: "mcp_tool_result"

        • tool_use_id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or array of BetaTextBlockParam

          • string

          • BetaMCPToolResultBlockParamContent = array of BetaTextBlockParam

            • type: "text"

            • text: string

              minLength: 1

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • citations: optional array of BetaTextCitationParam or null

        • is_error: optional boolean

      • BetaContainerUploadBlockParam object

        A content block that represents a file to be uploaded to the container Files uploaded via this block will be available in the container's input directory.

        • type: "container_upload"

        • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaCompactionBlockParam object

        A compaction block containing summary of previous context.

        Users should round-trip these blocks from responses to subsequent requests to maintain context across compaction boundaries.

        When content is None, the block represents a failed compaction. The server treats these as no-ops. Empty string content is not allowed.

        • type: "compaction"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or null

          Summary of previously compacted content, or null if compaction failed

        • encrypted_content: optional string or null

          Opaque metadata from prior compaction, to be round-tripped verbatim

      • BetaRequestToolAdditionBlock object

        Mid-conversation directive to surface a declared tool.

        tool references a tool (or MCP toolset) by name from the request's tools; it is offered to the model from this point in the conversation onward.

        • type: "tool_addition"

        • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

          Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeToolReference object

            Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

            • type: "tool_reference"

            • name: string

              pattern: ^[a-zA-Z0-9_-]{1,128}$

          • BetaToolChangeMCPToolReference object

            Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

            • type: "mcp_tool_reference"

            • name: string

            • server_name: string

          • BetaToolChangeMCPToolsetReference object

            Reference to every tool in the named MCP server's toolset.

            • type: "mcp_toolset_reference"

            • server_name: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaRequestToolRemovalBlock object

        Mid-conversation directive to withdraw a tool.

        tool references a tool (or MCP toolset) by name from the request's tools; it is no longer offered to the model from this point in the conversation onward.

        • type: "tool_removal"

        • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

          Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeToolReference object

            Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeMCPToolReference object

            Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

          • BetaToolChangeMCPToolsetReference object

            Reference to every tool in the named MCP server's toolset.

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaFallbackBlockParam object

        A fallback block echoed back from a prior response.

        Accepted in messages[].content and not rendered into the prompt; not validated against the request's fallbacks chain or top-level model.

        Echo the assistant turn back verbatim, including this block in its original position. The block marks the boundary between content produced before and after a fallback hop, and the server relies on that boundary to validate the turn: when thinking runs flank the boundary, omitting the block merges them into one span the server cannot validate (the request is rejected), and moving it into the middle of a single run is likewise rejected; between non-thinking blocks the block's placement has no validation effect.

        • type: "fallback"

        • from: BetaFallbackInfoParam

          Identifies one hop of a fallback transition.

          • model: Model

            The model that will complete your prompt.

            See models for additional details and options.

            • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

              The model that will complete your prompt.

              See models for additional details and options.

              • "claude-fable-5-1"

                Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

              • "claude-mythos-5-1"

                Our most capable model for cybersecurity and biology research, available through trusted access programs

              • "claude-sonnet-5"

                High-performance model for coding and agents

              • "claude-fable-5"

                Next generation of intelligence for the hardest knowledge work and coding problems

              • "claude-mythos-5"

                Most capable model for cybersecurity and biology research

              • "claude-opus-5"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-8"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-7"

                Powerful intelligence for long-running agents and coding

              • "claude-mythos-preview"

                New class of intelligence, strongest in coding and cybersecurity

              • "claude-opus-4-6"

                Powerful intelligence for long-running agents and coding

              • "claude-sonnet-4-6"

                Best combination of speed and intelligence

              • "claude-haiku-4-5"

                Fastest model with near-frontier intelligence

              • "claude-haiku-4-5-20251001"

                Fastest model with near-frontier intelligence

              • "claude-opus-4-5"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-5-20251101"

                Powerful intelligence for long-running agents and coding

              • "claude-sonnet-4-5"

                High-performance model for agents and coding

              • "claude-sonnet-4-5-20250929"

                High-performance model for agents and coding

            • string

        • to: BetaFallbackInfoParam

          Identifies one hop of a fallback transition.

        • trigger: optional unknown

          The response block's trigger, echoed verbatim. Accepted and ignored by the server; any object or null is allowed.

  • role: "user" or "assistant" or "system"

    • "user"

    • "assistant"

    • "system"

  • clear_at: optional "next_user_message" or "never" or null

    How long this system message's text stays in front of the model. "never" (the default) renders it on every request that includes it. "next_user_message" renders it only for the user turn it follows: once a later role: "user" message exists in messages the message stays in the array (send it unchanged) but is no longer shown to the model. Only permitted on role: "system" messages.

    • "next_user_message"

    • "never"

  • output_config: optional BetaSystemMessageOutputConfig or null

    Per-message output configuration on a role:"system" input message.

    Fields here apply per-turn; format remains top-level only. An empty \{\} is accepted on a message that carries content; a message with neither content nor output_config fields is rejected.

    • effort: optional "low" or "medium" or "high" or 2 more or null

      All possible effort levels.

      • "low"

      • "medium"

      • "high"

      • "xhigh"

      • "max"

• model: Model

  The model that will complete your prompt.

  See models for additional details and options.

• cache_control: optional BetaCacheControlEphemeral or null

  Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.

• container: optional BetaContainerParams or string or null

  Container identifier for reuse across requests.

  • BetaContainerParams object

    Container parameters with skills to be loaded.

    • id: optional string or null

      Container id

    • skills: optional array of BetaSkillParams or null

      List of skills to load in the container

      maxItems: 20

      • type: "anthropic" or "custom"

        Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

        • "anthropic"

        • "custom"

      • skill_id: string

        Skill ID

        maxLength: 64, minLength: 1

      • version: optional string

        Skill version or 'latest' for most recent version

        maxLength: 64, minLength: 1

  • string

• context_management: optional BetaContextManagementConfig or null

  Context management configuration.

  This allows you to control how Claude manages context across multiple requests, such as whether to clear function results or not.

  • edits: optional array of BetaClearToolUses20250919Edit or BetaClearThinking20251015Edit or BetaCompact20260112Edit

    List of context management edits to apply

    minItems: 0

    • BetaClearToolUses20250919Edit object

      • type: "clear_tool_uses_20250919"

      • clear_at_least: optional BetaInputTokensClearAtLeast or null

        Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

        • type: "input_tokens"

        • value: number

          minimum: 0

      • clear_tool_inputs: optional boolean or array of string or null

        Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

        • boolean

        • array of string

      • exclude_tools: optional array of string or null

        Tool names whose uses are preserved from clearing

      • keep: optional BetaToolUsesKeep

        Number of tool uses to retain in the conversation

        • type: "tool_uses"

        • value: number

          minimum: 0

      • trigger: optional BetaInputTokensTrigger or BetaToolUsesTrigger

        Condition that triggers the context management strategy

        • BetaInputTokensTrigger object

          • type: "input_tokens"

          • value: number

            minimum: 1

        • BetaToolUsesTrigger object

          • type: "tool_uses"

          • value: number

            minimum: 1

    • BetaClearThinking20251015Edit object

      • type: "clear_thinking_20251015"

      • keep: optional BetaThinkingTurns or BetaAllThinkingTurns or "all"

        Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

        • BetaThinkingTurns object

          • type: "thinking_turns"

          • value: number

            minimum: 1

        • BetaAllThinkingTurns object

          • type: "all"

        • "all"

    • BetaCompact20260112Edit object

      Automatically compact older context when reaching the configured trigger threshold.

      • type: "compact_20260112"

      • instructions: optional string or null

        Additional instructions for summarization.

      • pause_after_compaction: optional boolean

        Whether to pause after compaction and return the compaction block to the user.

      • trigger: optional BetaInputTokensTrigger or null

        When to trigger compaction. Defaults to 150000 input tokens.

• diagnostics: optional BetaDiagnosticsParam or null

  Request-level diagnostics. Currently carries the previous response id for prompt-cache divergence reporting.

  • previous_message_id: optional string or null

    The id (msg_...) from this client's previous /v1/messages response. The server compares that request's prompt fingerprint against this one and returns diagnostics.cache_miss_reason when the prompt-cache prefix could not be reused. Pass null on the first turn to opt in without a prior message to compare.

    maxLength: 256

• fallback_credit_token: optional string or BetaFallbackCreditTokenParam or null

  The fallback_credit_token from a prior refusal's stop_details.

  When a preceding request was refused and returned a fallback_credit_token, pass that code here on the retry to have the retry's cache-creation tokens for the prefix that was warm on the refused model billed at the cache-read rate. Must be redeemed by the same organization and workspace, with the same request body (optionally extended by one appended assistant message whose content is the partial text — with any trailing whitespace stripped from the final text block — and paired server-tool blocks streamed before the refusal; the appended-assistant form is not available for requests with output_format set or forced tool_choice), on an eligible fallback model, on the same platform, and within 5 minutes of the refusal; a mismatch is a 400. A token minted mid-server-tool-loop whose partial content was continuable may only be redeemed with the appended-assistant form — if an exact-body retry is rejected with a 400 saying the token must be redeemed by continuing the partial response, retry with the appended-assistant form instead.

  When the appended-assistant form is used on a model that otherwise disallows assistant-turn prefill, this token also authorizes that one prefill.

  • string

  • BetaFallbackCreditTokenParam object

    Object form of fallback_credit_token: the token plus a redemption mode.

    Requires anthropic-beta: fallback-credit-2026-07-01; without that header the field accepts the bare string only. The bare string and the mode-less object are equivalent (both select strict), so wrapping an existing token changes nothing by itself.

    • token: string

      The opaque fallback_credit_token from a prior refusal's stop_details — the same string the bare-string form carries.

      maxLength: 2048, minLength: 1

    • mode: optional "strict" or "best_effort"

      How a failing token affects the retry. strict (the default, and the bare-string behavior): a failing redemption is a 400 and the retry is not served. best_effort: the retry is served either way — a token-layer failure no longer rejects the request; the retry proceeds at normal price and the outcome is reported on the response's usage.fallback_credit. Two failures stay hard in both modes: a malformed token, and combining fallback_credit_token with fallbacks.

      • "strict"

      • "best_effort"

• fallbacks: optional BetaFallbacksParam or null

  Opt-in server-side retry on one or more substitute models when the requested model declines for policy reasons. Tried in order: if the first entry also declines, the second is tried, and so on. The string "default" requests the requested model's server-defined default fallback configuration.

  • array of BetaFallbackParam

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

    • max_tokens: optional number or null

    • output_config: optional BetaOutputConfig or null

      • effort: optional "low" or "medium" or "high" or 2 more or null

        All possible effort levels.

        • "low"

        • "medium"

        • "high"

        • "xhigh"

        • "max"

      • format: optional BetaJSONOutputFormat or null

        A schema to specify Claude's output format in responses. See structured outputs

        • type: "json_schema"

        • schema: map[unknown]

          The JSON schema of the format

      • task_budget: optional BetaTokenTaskBudget or null

        User-configurable total token budget across contexts.

        • type: "tokens"

          The budget type. Currently only 'tokens' is supported.

        • total: number

          Total token budget across all contexts in the session.

          minimum: 1024

        • remaining: optional number or null

          Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

          minimum: 0

    • speed: optional "standard" or "fast" or null

      Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

      • "standard"

      • "fast"

    • thinking: optional BetaThinkingConfigEnabled or BetaThinkingConfigDisabled or BetaThinkingConfigAdaptive or null

      • BetaThinkingConfigEnabled object

        • type: "enabled"

        • budget_tokens: number

          Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

          Must be ≥1024 and less than max_tokens.

          See extended thinking for details.

          minimum: 1024

        • block_binding: optional BetaThinkingBlockBinding or null

          Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

          • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

            What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

            • "error"

            • "drop_block"

        • display: optional "summarized" or "omitted" or "updates" or null

          Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

          • "summarized"

          • "omitted"

          • "updates"

      • BetaThinkingConfigDisabled object

        • type: "disabled"

      • BetaThinkingConfigAdaptive object

        • type: "adaptive"

        • block_binding: optional BetaThinkingBlockBinding or null

          Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

        • display: optional "summarized" or "omitted" or "updates" or null

          Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

          • "summarized"

          • "omitted"

          • "updates"

  • Default = "default"

• inference_geo: optional string or null

  Specifies the geographic region for inference processing. If not specified, the workspace's default_inference_geo is used.

• mcp_servers: optional array of BetaRequestMCPServerURLDefinition

  MCP servers to be utilized in this request

  maxItems: 20

  • type: "url"

  • name: string

  • url: string

  • authorization_token: optional string or null

  • tool_configuration: optional BetaRequestMCPServerToolConfiguration or null

    • allowed_tools: optional array of string or null

    • enabled: optional boolean or null

• metadata: optional BetaMetadata

  An object describing metadata about the request.

  • user_id: optional string or null

    An external identifier for the user who is associated with the request.

    This should be a uuid, hash value, or other opaque identifier. Anthropic may use this id to help detect abuse. Do not include any identifying information such as name, email address, or phone number.

    maxLength: 512

• output_config: optional BetaOutputConfig

  Configuration options for the model's output, such as the output format.

• service_tier: optional "auto" or "standard_only"

  Determines whether to use priority capacity (if available) or standard capacity for this request.

  Anthropic offers different levels of service for your API requests. See service-tiers for details.

  • "auto"

  • "standard_only"

• speed: optional "standard" or "fast" or null

  Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

  • "standard"

  • "fast"

• stop_sequences: optional array of string

  Custom text sequences that will cause the model to stop generating.

  Our models will normally stop when they have naturally completed their turn, which will result in a response stop_reason of "end_turn".

  If you want the model to stop generating when it encounters custom strings of text, you can use the stop_sequences parameter. If the model encounters one of the custom sequences, the response stop_reason value will be "stop_sequence" and the response stop_sequence value will contain the matched stop sequence.

• stream: optional boolean

  Whether to incrementally stream the response using server-sent events.

  See streaming for details.

• system: optional string or array of BetaTextBlockParam

  System prompt.

  A system prompt is a way of providing context and instructions to Claude, such as specifying a particular goal or role. See our guide to system prompts.

  • string

  • array of BetaTextBlockParam

    • type: "text"

    • text: string

      minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional array of BetaTextCitationParam or null

• thinking: optional BetaThinkingConfigParam

  Configuration for enabling Claude's extended thinking.

  When enabled, responses include thinking content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your max_tokens limit.

  See extended thinking for details.

  • BetaThinkingConfigEnabled object

  • BetaThinkingConfigDisabled object

  • BetaThinkingConfigAdaptive object

• tool_choice: optional BetaToolChoice

  How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

  • BetaToolChoiceAuto object

    The model will automatically decide whether to use tools.

    • type: "auto"

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output at most one tool use.

  • BetaToolChoiceAny object

    The model will use any available tools.

    • type: "any"

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output exactly one tool use.

  • BetaToolChoiceTool object

    The model will use the specified tool with tool_choice.name.

    • type: "tool"

    • name: string

      The name of the tool to use.

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output exactly one tool use.

  • BetaToolChoiceNone object

    The model will not be allowed to use tools.

    • type: "none"

• tools: optional array of BetaToolUnion

  Definitions of tools that the model may use.

  If you include tools in your API request, the model may return tool_use content blocks that represent the model's use of those tools. You can then run those tools using the tool input generated by the model and then optionally return results back to the model using tool_result content blocks.

  There are two types of tools: client tools and server tools. The behavior described below applies to client tools. For server tools, see their individual documentation as each has its own behavior (e.g., the web search tool).

  Each tool definition includes:

  • name: Name of the tool.
  • description: Optional, but strongly-recommended description of the tool.
  • input_schema: JSON schema for the tool input shape that the model will produce in tool_use output content blocks.

  For example, if you defined tools as:

  [
    {
      "name": "get_stock_price",
      "description": "Get the current stock price for a given ticker symbol.",
      "input_schema": {
        "type": "object",
        "properties": {
          "ticker": {
            "type": "string",
            "description": "The stock ticker symbol, e.g. AAPL for Apple Inc."
          }
        },
        "required": ["ticker"]
      }
    }
  ]

  And then asked the model "What's the S&P 500 at today?", the model might produce tool_use content blocks in the response like this:

  [
    {
      "type": "tool_use",
      "id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "name": "get_stock_price",
      "input": { "ticker": "^GSPC" }
    }
  ]

  You might then run your get_stock_price tool with \{"ticker": "^GSPC"\} as an input, and return the following back to the model in a subsequent user message:

  [
    {
      "type": "tool_result",
      "tool_use_id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "content": "259.75 USD"
    }
  ]

  Tools can be used for workflows that include running client-side tools and functions, or more generally whenever you want the model to produce a particular JSON structure of output.

  See our guide for more details.

  • BetaTool object

    • type: optional "custom" or null

    • input_schema: object

      JSON schema for this tool's input.

      This defines the shape of the input that your tool accepts and that the model will produce.

      • type: "object"

      • properties: optional map[unknown] or null

      • required: optional array of string or null

    • name: string

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

      maxLength: 128, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,128}$

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • description: optional string

      Description of what this tool does.

      Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

    • eager_input_streaming: optional boolean or null

      Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolBash20241022 object

    • type: "bash_20241022"

    • name: "bash"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolBash20250124 object

    • type: "bash_20250124"

    • name: "bash"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20250522 object

    • type: "code_execution_20250522"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20250825 object

    • type: "code_execution_20250825"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20260120 object

    Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

    • type: "code_execution_20260120"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20260521 object

    Code execution tool with REPL state persistence.

    • type: "code_execution_20260521"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaBrowserToolset20260801 object

    The browser toolset: a single tools[] entry (carrying no name) that declares the browser tool family. The model is served the family's tool with any members disabled via configs removed from its schema.

    • type: "browser_toolset_20260801"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional BetaBrowserToolsetConfigs or null

      Per-member configuration for browser_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

      • type: optional BetaBrowserTypeConfig or null

        type's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • close_tab: optional BetaBrowserCloseTabConfig or null

        close_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • double_click: optional BetaBrowserDoubleClickConfig or null

        double_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • file_upload: optional BetaBrowserFileUploadConfig or null

        file_upload's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • find: optional BetaBrowserFindConfig or null

        find's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • form_input: optional BetaBrowserFormInputConfig or null

        form_input's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • get_page_text: optional BetaBrowserGetPageTextConfig or null

        get_page_text's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hold_key: optional BetaBrowserHoldKeyConfig or null

        hold_key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hover: optional BetaBrowserHoverConfig or null

        hover's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • javascript_exec: optional BetaBrowserJavascriptExecConfig or null

        javascript_exec's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • key: optional BetaBrowserKeyConfig or null

        key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click: optional BetaBrowserLeftClickConfig or null

        left_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click_drag: optional BetaBrowserLeftClickDragConfig or null

        left_click_drag's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_down: optional BetaBrowserLeftMouseDownConfig or null

        left_mouse_down's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_up: optional BetaBrowserLeftMouseUpConfig or null

        left_mouse_up's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • list_tabs: optional BetaBrowserListTabsConfig or null

        list_tabs's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • middle_click: optional BetaBrowserMiddleClickConfig or null

        middle_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • mouse_move: optional BetaBrowserMouseMoveConfig or null

        mouse_move's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • navigate: optional BetaBrowserNavigateConfig or null

        navigate's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • new_tab: optional BetaBrowserNewTabConfig or null

        new_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_console: optional BetaBrowserReadConsoleConfig or null

        read_console's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_network: optional BetaBrowserReadNetworkConfig or null

        read_network's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_page: optional BetaBrowserReadPageConfig or null

        read_page's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • right_click: optional BetaBrowserRightClickConfig or null

        right_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • screenshot: optional BetaBrowserScreenshotConfig or null

        screenshot's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll: optional BetaBrowserScrollConfig or null

        scroll's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll_to: optional BetaBrowserScrollToConfig or null

        scroll_to's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • switch_tab: optional BetaBrowserSwitchTabConfig or null

        switch_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • triple_click: optional BetaBrowserTripleClickConfig or null

        triple_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • wait: optional BetaBrowserWaitConfig or null

        wait's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • zoom: optional BetaBrowserZoomConfig or null

        zoom's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • BetaToolComputerUse20241022 object

    • type: "computer_20241022"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaMemoryTool20250818 object

    • type: "memory_20250818"

    • name: "memory"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolComputerUse20250124 object

    • type: "computer_20250124"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20241022 object

    • type: "text_editor_20241022"

    • name: "str_replace_editor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolComputerUse20251124 object

    • type: "computer_20251124"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • enable_zoom: optional boolean

      Whether to enable an action to take a zoomed-in screenshot of the screen.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaComputerToolset20260801 object

    The computer toolset: a single tools[] entry (carrying no name) that declares the computer tool family. The model is served the family's tool with any members disabled via configs removed from its schema. Every member is enabled by default, zoom included. The single-tool options display_number and enable_zoom are not fields of a toolset entry — it carries only type, configs, and cache_control; zoom is controlled via configs.zoom.enabled.

    • type: "computer_toolset_20260801"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional BetaComputerToolsetConfigs or null

      Per-member configuration for computer_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

      • type: optional BetaComputerTypeConfig or null

        type's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • cursor_position: optional BetaComputerCursorPositionConfig or null

        cursor_position's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • double_click: optional BetaComputerDoubleClickConfig or null

        double_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hold_key: optional BetaComputerHoldKeyConfig or null

        hold_key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • key: optional BetaComputerKeyConfig or null

        key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click: optional BetaComputerLeftClickConfig or null

        left_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click_drag: optional BetaComputerLeftClickDragConfig or null

        left_click_drag's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_down: optional BetaComputerLeftMouseDownConfig or null

        left_mouse_down's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_up: optional BetaComputerLeftMouseUpConfig or null

        left_mouse_up's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • middle_click: optional BetaComputerMiddleClickConfig or null

        middle_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • mouse_move: optional BetaComputerMouseMoveConfig or null

        mouse_move's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • right_click: optional BetaComputerRightClickConfig or null

        right_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • screenshot: optional BetaComputerScreenshotConfig or null

        screenshot's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll: optional BetaComputerScrollConfig or null

        scroll's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • triple_click: optional BetaComputerTripleClickConfig or null

        triple_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • wait: optional BetaComputerWaitConfig or null

        wait's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • zoom: optional BetaComputerZoomConfig or null

        zoom's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • BetaToolTextEditor20250124 object

    • type: "text_editor_20250124"

    • name: "str_replace_editor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20250429 object

    • type: "text_editor_20250429"

    • name: "str_replace_based_edit_tool"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20250728 object

    • type: "text_editor_20250728"

    • name: "str_replace_based_edit_tool"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • max_characters: optional number or null

      Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

      minimum: 1

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebSearchTool20250305 object

    • type: "web_search_20250305"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

      • type: "approximate"

      • city: optional string or null

        The city of the user.

        maxLength: 255, minLength: 1

      • country: optional string or null

        The two letter ISO country code of the user.

        maxLength: 2, minLength: 2

      • region: optional string or null

        The region of the user.

        maxLength: 255, minLength: 1

      • timezone: optional string or null

        The IANA timezone of the user.

        maxLength: 255, minLength: 1

  • BetaWebFetchTool20250910 object

    • type: "web_fetch_20250910"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebSearchTool20260209 object

    • type: "web_search_20260209"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

  • BetaWebFetchTool20260209 object

    • type: "web_fetch_20260209"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebFetchTool20260309 object

    Web fetch tool with use_cache parameter for bypassing cached content.

    • type: "web_fetch_20260309"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • use_cache: optional boolean

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  • BetaWebSearchTool20260318 object

    • type: "web_search_20260318"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • response_inclusion: optional "full" or "excluded"

      How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

      • "full"

      • "excluded"

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

  • BetaWebFetchTool20260318 object

    • type: "web_fetch_20260318"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • response_inclusion: optional "full" or "excluded"

      How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

      • "full"

      • "excluded"

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • use_cache: optional boolean

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  • BetaAdvisorTool20260301 object

    • type: "advisor_20260301"

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

    • name: "advisor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • caching: optional BetaCacheControlEphemeral or null

      Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_tokens: optional number or null

      Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

      minimum: 1024

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolSearchToolBm25_20251119 object

    • type: "tool_search_tool_bm25_20251119" or "tool_search_tool_bm25"

      • "tool_search_tool_bm25_20251119"

      • "tool_search_tool_bm25"

    • name: "tool_search_tool_bm25"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolSearchToolRegex20251119 object

    • type: "tool_search_tool_regex_20251119" or "tool_search_tool_regex"

      • "tool_search_tool_regex_20251119"

      • "tool_search_tool_regex"

    • name: "tool_search_tool_regex"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaMCPToolset object

    Configuration for a group of tools from an MCP server.

    Allows configuring enabled status and defer_loading for all tools from an MCP server, with optional per-tool overrides.

    • type: "mcp_toolset"

    • mcp_server_name: string

      Name of the MCP server to configure tools for

      maxLength: 255, minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional map[BetaMCPToolConfig] or null

      Configuration overrides for specific tools, keyed by tool name

      • defer_loading: optional boolean

      • enabled: optional boolean

    • default_config: optional BetaMCPToolDefaultConfig

      Default configuration applied to all tools from this server

      • defer_loading: optional boolean

      • enabled: optional boolean

• output_format: optional BetaJSONOutputFormat or null

  Deprecated

  Deprecated: Use output_config.format instead. See structured outputs

  A schema to specify Claude's output format in responses. This parameter will be removed in a future release.

• temperature: optional number

  Deprecated: Deprecated. Models released after Claude Opus 4.6 do not support setting temperature. A value of 1.0 of will be accepted for backwards compatibility, all other values will be rejected with a 400 error.

  Amount of randomness injected into the response.

  Defaults to 1.0. Ranges from 0.0 to 1.0. Use temperature closer to 0.0 for analytical / multiple choice, and closer to 1.0 for creative and generative tasks.

  Note that even with temperature of 0.0, the results will not be fully deterministic.

  maximum: 1, minimum: 0

• top_k: optional number

  Deprecated: Deprecated. Models released after Claude Opus 4.6 do not accept top_k; any value will be rejected with a 400 error.

  Only sample from the top K options for each subsequent token.

  Used to remove "long tail" low probability responses. Learn more technical details here.

  Recommended for advanced use cases only.

  minimum: 0

• top_p: optional number

  Deprecated: Deprecated. Models released after Claude Opus 4.6 do not support setting top_p. A value >= 0.99 will be accepted for backwards compatibility, all other values will be rejected with a 400 error.

  Use nucleus sampling.

  In nucleus sampling, we compute the cumulative distribution over all the options for each subsequent token in decreasing probability order and cut it off once it reaches a particular probability specified by top_p.

  Recommended for advanced use cases only.

  maximum: 1, minimum: 0

Returns

• BetaMessage object

  • type: "message"

    Object type.

    For Messages, this is always "message".

    default: message

  • id: string

    Unique object identifier.

    The format and length of IDs may change over time.

  • container: BetaContainer or null

    Information about the container used in the request (for the code execution tool)

    • id: string

      Identifier for the container used in this request

    • expires_at: string

      The time at which the container will expire.

      format: date-time

    • skills: array of BetaContainerSkill or null

      Skills loaded in the container

      • type: "anthropic" or "custom"

        Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

        • "anthropic"

        • "custom"

      • skill_id: string

        Skill ID

        maxLength: 64, minLength: 1

      • version: string

        The resolved version: a skill version ID for custom skills.

        maxLength: 64, minLength: 1

  • content: array of BetaContentBlock

    Content generated by the model.

    This is an array of content blocks, each of which has a type that determines its shape.

    Example:

    [{"type": "text", "text": "Hi, I'm Claude."}]

    If the request input messages ended with an assistant turn, then the response content will continue directly from that last turn. You can use this to constrain the model's output.

    For example, if the input messages were:

    [
      {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
      {"role": "assistant", "content": "The best answer is ("}
    ]

    Then the response content might be:

    [{"type": "text", "text": "B)"}]

    • BetaTextBlock object

      • type: "text"

        default: text

      • citations: array of BetaTextCitation or null

        Citations supporting the text block.

        The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

        • BetaCitationCharLocation object

          • type: "char_location"

            default: char_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_char_index: number

          • file_id: string or null

          • start_char_index: number

            minimum: 0

        • BetaCitationPageLocation object

          • type: "page_location"

            default: page_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_page_number: number

          • file_id: string or null

          • start_page_number: number

            minimum: 1

        • BetaCitationContentBlockLocation object

          • type: "content_block_location"

            default: content_block_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • file_id: string or null

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

        • BetaCitationsWebSearchResultLocation object

          • type: "web_search_result_location"

            default: web_search_result_location

          • cited_text: string

          • encrypted_index: string

          • title: string or null

            maxLength: 512

          • url: string

        • BetaCitationSearchResultLocation object

          • type: "search_result_location"

            default: search_result_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • search_result_index: number

            0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from document_index; server-side web search results are not included in this count.

            minimum: 0

          • source: string

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

          • title: string or null

      • text: string

        minLength: 0

    • BetaThinkingBlock object

      • type: "thinking"

        default: thinking

      • signature: string

        A value used to verify that this thinking block was generated by Claude when it is passed back to the API.

        This is an opaque field and should not be interpreted or parsed. When passing thinking blocks back to the API (required when using tools with extended thinking), pass them back exactly as received, with this field intact.

        See extended thinking for details.

      • thinking: string

        The text of Claude's thinking process for this block.

    • BetaRedactedThinkingBlock object

      • type: "redacted_thinking"

        default: redacted_thinking

      • data: string

        The contents of this redacted thinking block, returned when portions of the model's thinking were safety-redacted. This field is opaque and encrypted, with no readable content.

        Pass redacted_thinking blocks back to the API unchanged when continuing a multi-turn conversation.

        See extended thinking for details.

    • BetaToolUseBlock object

      • type: "tool_use"

        default: tool_use

      • id: string

        pattern: ^[a-zA-Z0-9_-]+$

      • input: map[unknown]

      • name: string

        minLength: 1

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

          • type: "direct"

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

          • type: "code_execution_20250825"

          • tool_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • BetaServerToolCaller20260120 object

          • type: "code_execution_20260120"

          • tool_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • toolset_name: optional string or null

        For a toolset member tool_use, the toolset family.

        maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

    • BetaServerToolUseBlock object

      • type: "server_tool_use"

        default: server_tool_use

      • id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • input: map[unknown]

      • name: "advisor" or "web_search" or "web_fetch" or 5 more

        • "advisor"

        • "web_search"

        • "web_fetch"

        • "code_execution"

        • "bash_code_execution"

        • "text_editor_code_execution"

        • "tool_search_tool_regex"

        • "tool_search_tool_bm25"

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaWebSearchToolResultBlock object

      • type: "web_search_tool_result"

        default: web_search_tool_result

      • content: BetaWebSearchToolResultBlockContent

        • BetaWebSearchToolResultError object

          • type: "web_search_tool_result_error"

            default: web_search_tool_result_error

          • error_code: BetaWebSearchToolResultErrorCode

            • "invalid_tool_input"

            • "unavailable"

            • "max_uses_exceeded"

            • "too_many_requests"

            • "query_too_long"

            • "request_too_large"

        • array of BetaWebSearchResultBlock

          • type: "web_search_result"

            default: web_search_result

          • encrypted_content: string

          • page_age: string or null

          • title: string

          • url: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaWebFetchToolResultBlock object

      • type: "web_fetch_tool_result"

        default: web_fetch_tool_result

      • content: BetaWebFetchToolResultErrorBlock or BetaWebFetchBlock

        • BetaWebFetchToolResultErrorBlock object

          • type: "web_fetch_tool_result_error"

            default: web_fetch_tool_result_error

          • error_code: BetaWebFetchToolResultErrorCode

            • "invalid_tool_input"

            • "url_too_long"

            • "url_not_allowed"

            • "url_not_in_prior_context"

            • "url_not_accessible"

            • "unsupported_content_type"

            • "too_many_requests"

            • "max_uses_exceeded"

            • "unavailable"

            • "content_too_large"

        • BetaWebFetchBlock object

          • type: "web_fetch_result"

            default: web_fetch_result

          • content: BetaDocumentBlock

            • type: "document"

              default: document

            • citations: BetaCitationConfig or null

              Citation configuration for the document

              • enabled: boolean

                default: false

            • source: BetaBase64PDFSource or BetaPlainTextSource

              • BetaBase64PDFSource object

                • type: "base64"

                • data: string

                  format: byte

                • media_type: "application/pdf"

              • BetaPlainTextSource object

                • type: "text"

                • data: string

                • media_type: "text/plain"

            • title: string or null

              The title of the document

          • retrieved_at: string or null

            ISO 8601 timestamp when the content was retrieved

          • url: string

            Fetched content URL

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaAdvisorToolResultBlock object

      • type: "advisor_tool_result"

        default: advisor_tool_result

      • content: BetaAdvisorToolResultError or BetaAdvisorResultBlock or BetaAdvisorRedactedResultBlock

        • BetaAdvisorToolResultError object

          • type: "advisor_tool_result_error"

            default: advisor_tool_result_error

          • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

            • "max_uses_exceeded"

            • "prompt_too_long"

            • "too_many_requests"

            • "overloaded"

            • "unavailable"

            • "execution_time_exceeded"

            • "model_not_found"

        • BetaAdvisorResultBlock object

          • type: "advisor_result"

            default: advisor_result

          • stop_reason: string or null

            The advisor sub-inference's stop reason (same values as the top-level message stop_reason). max_tokens indicates the advisor's output was truncated at the tool's max_tokens value or the advisor model's policy cap.

          • text: string

        • BetaAdvisorRedactedResultBlock object

          • type: "advisor_redacted_result"

            default: advisor_redacted_result

          • encrypted_content: string

            Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

          • stop_reason: string or null

            The advisor sub-inference's stop reason (same values as the top-level message stop_reason).

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaCodeExecutionToolResultBlock object

      • type: "code_execution_tool_result"

        default: code_execution_tool_result

      • content: BetaCodeExecutionToolResultBlockContent

        Code execution result with encrypted stdout for PFC + web_search results.

        • BetaCodeExecutionToolResultError object

          • type: "code_execution_tool_result_error"

            default: code_execution_tool_result_error

          • error_code: BetaCodeExecutionToolResultErrorCode

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

        • BetaCodeExecutionResultBlock object

          • type: "code_execution_result"

            default: code_execution_result

          • content: array of BetaCodeExecutionOutputBlock

            • type: "code_execution_output"

              default: code_execution_output

            • file_id: string

          • return_code: number

          • stderr: string

          • stdout: string

        • BetaEncryptedCodeExecutionResultBlock object

          Code execution result with encrypted stdout for PFC + web_search results.

          • type: "encrypted_code_execution_result"

            default: encrypted_code_execution_result

          • content: array of BetaCodeExecutionOutputBlock

            • type: "code_execution_output"

              default: code_execution_output

            • file_id: string

          • encrypted_stdout: string

          • return_code: number

          • stderr: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaBashCodeExecutionToolResultBlock object

      • type: "bash_code_execution_tool_result"

        default: bash_code_execution_tool_result

      • content: BetaBashCodeExecutionToolResultError or BetaBashCodeExecutionResultBlock

        • BetaBashCodeExecutionToolResultError object

          • type: "bash_code_execution_tool_result_error"

            default: bash_code_execution_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

            • "output_file_too_large"

        • BetaBashCodeExecutionResultBlock object

          • type: "bash_code_execution_result"

            default: bash_code_execution_result

          • content: array of BetaBashCodeExecutionOutputBlock

            • type: "bash_code_execution_output"

              default: bash_code_execution_output

            • file_id: string

          • return_code: number

          • stderr: string

          • stdout: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaTextEditorCodeExecutionToolResultBlock object

      • type: "text_editor_code_execution_tool_result"

        default: text_editor_code_execution_tool_result

      • content: BetaTextEditorCodeExecutionToolResultError or BetaTextEditorCodeExecutionViewResultBlock or BetaTextEditorCodeExecutionCreateResultBlock or BetaTextEditorCodeExecutionStrReplaceResultBlock

        • BetaTextEditorCodeExecutionToolResultError object

          • type: "text_editor_code_execution_tool_result_error"

            default: text_editor_code_execution_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

            • "file_not_found"

          • error_message: string or null

        • BetaTextEditorCodeExecutionViewResultBlock object

          • type: "text_editor_code_execution_view_result"

            default: text_editor_code_execution_view_result

          • content: string

          • file_type: "text" or "image" or "pdf"

            • "text"

            • "image"

            • "pdf"

          • num_lines: number or null

          • start_line: number or null

          • total_lines: number or null

        • BetaTextEditorCodeExecutionCreateResultBlock object

          • type: "text_editor_code_execution_create_result"

            default: text_editor_code_execution_create_result

          • is_file_update: boolean

        • BetaTextEditorCodeExecutionStrReplaceResultBlock object

          • type: "text_editor_code_execution_str_replace_result"

            default: text_editor_code_execution_str_replace_result

          • lines: array of string or null

          • new_lines: number or null

          • new_start: number or null

          • old_lines: number or null

          • old_start: number or null

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaToolSearchToolResultBlock object

      • type: "tool_search_tool_result"

        default: tool_search_tool_result

      • content: BetaToolSearchToolResultError or BetaToolSearchToolSearchResultBlock

        • BetaToolSearchToolResultError object

          • type: "tool_search_tool_result_error"

            default: tool_search_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

          • error_message: string or null

        • BetaToolSearchToolSearchResultBlock object

          • type: "tool_search_tool_search_result"

            default: tool_search_tool_search_result

          • tool_references: array of BetaToolReferenceBlock

            • type: "tool_reference"

              default: tool_reference

            • tool_name: string

              maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaMCPToolUseBlock object

      • type: "mcp_tool_use"

        default: mcp_tool_use

      • id: string

        pattern: ^[a-zA-Z0-9_-]+$

      • input: map[unknown]

      • name: string

        The name of the MCP tool

      • server_name: string

        The name of the MCP server

    • BetaMCPToolResultBlock object

      • type: "mcp_tool_result"

        default: mcp_tool_result

      • content: string or array of BetaTextBlock

        • string

        • BetaMCPToolResultBlockContent = array of BetaTextBlock

          • type: "text"

            default: text

          • citations: array of BetaTextCitation or null

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

          • text: string

            minLength: 0

      • is_error: boolean

        default: false

      • tool_use_id: string

        pattern: ^[a-zA-Z0-9_-]+$

    • BetaContainerUploadBlock object

      Response model for a file uploaded to the container.

      • type: "container_upload"

        default: container_upload

      • file_id: string

    • BetaCompactionBlock object

      A compaction block returned when autocompact is triggered.

      When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

      • type: "compaction"

        default: compaction

      • content: string or null

        Summary of compacted content, or null if compaction failed

      • encrypted_content: string or null

        Opaque metadata from prior compaction, to be round-tripped verbatim

    • BetaFallbackBlock object

      Marks the point in content where one model's output gives way to the next.

      One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

      The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

      • type: "fallback"

        default: fallback

      • from: BetaFallbackInfo

        The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its model echoes the top-level model string the caller sent (alias or canonical); when the declining hop is a fallback model, its model is that model's canonical id.

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

          • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

            The model that will complete your prompt.

            See models for additional details and options.

            • "claude-fable-5-1"

              Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

            • "claude-mythos-5-1"

              Our most capable model for cybersecurity and biology research, available through trusted access programs

            • "claude-sonnet-5"

              High-performance model for coding and agents

            • "claude-fable-5"

              Next generation of intelligence for the hardest knowledge work and coding problems

            • "claude-mythos-5"

              Most capable model for cybersecurity and biology research

            • "claude-opus-5"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-8"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-7"

              Powerful intelligence for long-running agents and coding

            • "claude-mythos-preview"

              New class of intelligence, strongest in coding and cybersecurity

            • "claude-opus-4-6"

              Powerful intelligence for long-running agents and coding

            • "claude-sonnet-4-6"

              Best combination of speed and intelligence

            • "claude-haiku-4-5"

              Fastest model with near-frontier intelligence

            • "claude-haiku-4-5-20251001"

              Fastest model with near-frontier intelligence

            • "claude-opus-4-5"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-5-20251101"

              Powerful intelligence for long-running agents and coding

            • "claude-sonnet-4-5"

              High-performance model for agents and coding

            • "claude-sonnet-4-5-20250929"

              High-performance model for agents and coding

          • string

      • to: BetaFallbackInfo

        The fallback model producing the content that follows this block. Its model is always the canonical id.

      • trigger: BetaFallbackRefusalTrigger

        What caused the from model to hand over at this hop.

        • type: "refusal"

          default: refusal

        • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

          The policy category that triggered a refusal.

          • "cyber"

            The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

          • "bio"

            The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

          • "frontier_llm"

            The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

          • "reasoning_extraction"

            The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

          • "general_harms"

            The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

  • context_management: BetaContextManagementResponse or null

    Context management response.

    Information about context management strategies applied during the request.

    • applied_edits: array of BetaClearToolUses20250919EditResponse or BetaClearThinking20251015EditResponse

      List of context management edits that were applied.

      • BetaClearToolUses20250919EditResponse object

        • type: "clear_tool_uses_20250919"

          The type of context management edit applied.

          default: clear_tool_uses_20250919

        • cleared_input_tokens: number

          Number of input tokens cleared by this edit.

          minimum: 0

        • cleared_tool_uses: number

          Number of tool uses that were cleared.

          minimum: 0

      • BetaClearThinking20251015EditResponse object

        • type: "clear_thinking_20251015"

          The type of context management edit applied.

          default: clear_thinking_20251015

        • cleared_input_tokens: number

          Number of input tokens cleared by this edit.

          minimum: 0

        • cleared_thinking_turns: number

          Number of thinking turns that were cleared.

          minimum: 0

  • diagnostics: BetaDiagnostics or null

    Response envelope for request-level diagnostics. Present (possibly null) whenever the caller supplied diagnostics on the request.

    • cache_miss_reason: BetaCacheMissModelChanged or BetaCacheMissSystemChanged or BetaCacheMissToolsChanged or 3 more or null

      Explains why the prompt cache could not fully reuse the prefix from the request identified by diagnostics.previous_message_id. null means diagnosis is still pending — the response was serialized before the background comparison completed.

      • BetaCacheMissModelChanged object

        • type: "model_changed"

          default: model_changed

        • cache_missed_input_tokens: number

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      • BetaCacheMissSystemChanged object

        • type: "system_changed"

          default: system_changed

        • cache_missed_input_tokens: number

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      • BetaCacheMissToolsChanged object

        • type: "tools_changed"

          default: tools_changed

        • cache_missed_input_tokens: number

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      • BetaCacheMissMessagesChanged object

        • type: "messages_changed"

          default: messages_changed

        • cache_missed_input_tokens: number

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      • BetaCacheMissPreviousMessageNotFound object

        • type: "previous_message_not_found"

          default: previous_message_not_found

      • BetaCacheMissUnavailable object

        • type: "unavailable"

          default: unavailable

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

  • role: "assistant"

    Conversational role of the generated message.

    This will always be "assistant".

    default: assistant

  • stop_details: BetaRefusalStopDetails or null

    Structured information about a refusal.

    • type: "refusal"

      default: refusal

    • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

      The policy category that triggered a refusal.

      • "cyber"

        The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

      • "bio"

        The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

      • "frontier_llm"

        The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

      • "reasoning_extraction"

        The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

      • "general_harms"

        The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

    • explanation: string or null

      Human-readable explanation of the refusal.

      This text is not guaranteed to be stable. null when no explanation is available for the category.

    • fallback_credit_token: string or null

      Opaque code that refunds the cache-miss cost when retrying this refused request on the fallback model. Pass it as fallback_credit_token on the retry request. Expires 5 minutes after the refusal.

      The retry is sent either with the same request body (system, messages, tools, and other render-shaping fields), or with the same body plus one appended assistant message whose content is the partial text (with any trailing whitespace stripped from the final text block) and paired server-tool blocks from this refusal — which also authorizes that appended turn as an assistant-prefill continuation on models that otherwise disallow prefill. A token minted mid-server-tool-loop whose partial content was continuable may only be redeemed the second way — if a same-body retry is rejected with a 400 saying the token must be redeemed by continuing the partial response, retry the second way instead. Either way: same workspace, same platform; a mismatch is a 400. Resending a token for an already-warm prefix is permitted but yields no additional credit.

      null when the refused model isn't eligible for a fallback credit.

    • fallback_has_prefill_claim: boolean or null

      Whether the accompanying fallback_credit_token may be redeemed with the appended-assistant retry form. Only set when fallback_credit_token is present.

      true: retry by resending the same request body plus one appended assistant message whose content is this response's content with any trailing whitespace stripped from the final text block and unpaired tool_use blocks omitted (the same appended-turn shape described on fallback_credit_token), with the token attached. false: retry by resending the original request body unchanged, with the token attached — the appended-assistant form is not available for this refusal (no continuable partial content, or the request uses output_format or a tool_choice that forces tool use). One exception: when the request used output_format or a forced tool_choice and the refusal arrived after server tools (including MCP connector tools) had already executed, the token may not be redeemable by either retry form; if the exact-body retry is then rejected with a 400 saying the token must be redeemed by continuing the partial response, discard the token and retry without it.

      Advisory: if an appended-assistant retry is rejected with a 400 despite true, fall back to resending the original request body with the token.

    • recommended_model: string or null

      The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

  • stop_reason: BetaStopReason or null

    The reason that we stopped.

    This may be one the following values:

    • "end_turn": the model reached a natural stopping point
    • "max_tokens": we exceeded the requested max_tokens or the model's maximum
    • "stop_sequence": one of your provided custom stop_sequences was generated
    • "tool_use": the model invoked one or more tools
    • "pause_turn": we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
    • "refusal": when streaming classifiers intervene to handle potential policy violations
    • "model_context_window_exceeded": we exceeded the model's context window

    In non-streaming mode this value is always non-null. In streaming mode, it is null in the message_start event and non-null otherwise.

    • "end_turn"

    • "max_tokens"

    • "stop_sequence"

    • "tool_use"

    • "pause_turn"

    • "compaction"

    • "refusal"

    • "model_context_window_exceeded"

  • stop_sequence: string or null

    Which custom stop sequence was generated, if any.

    This value will be a non-null string if one of your custom stop sequences was generated.

  • usage: BetaUsage

    Billing and rate-limit usage.

    Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

    Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in usage will not match one-to-one with the exact visible content of an API request or response.

    For example, output_tokens will be non-zero, even for an empty string response from Claude.

    Total input tokens in a request is the summation of input_tokens, cache_creation_input_tokens, and cache_read_input_tokens.

    • cache_creation: BetaCacheCreation or null

      Breakdown of cached tokens by TTL

      • ephemeral_1h_input_tokens: number

        The number of input tokens used to create the 1 hour cache entry.

        default: 0, minimum: 0

      • ephemeral_5m_input_tokens: number

        The number of input tokens used to create the 5 minute cache entry.

        default: 0, minimum: 0

    • cache_creation_input_tokens: number or null

      The number of input tokens used to create the cache entry.

      minimum: 0

    • cache_read_input_tokens: number or null

      The number of input tokens read from the cache.

      minimum: 0

    • fallback_credit: BetaFallbackCreditUsage or null

      Outcome of the fallback_credit_token presented on this request.

      • status: BetaFallbackCreditRedeemed or BetaFallbackCreditNotApplied

        Whether the fallback-credit reprice was applied to this response's billing.

        A union discriminated on type. redeemed: the retry is billed as if the conversation had been on the retry model all along — including when the resulting shift is zero because there was nothing to move. not_applied: no reprice was applied; the arm's reason says why.

        • BetaFallbackCreditRedeemed object

          The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

          • type: "redeemed"

            default: redeemed

        • BetaFallbackCreditNotApplied object

          No reprice was applied; reason says why.

          • type: "not_applied"

            default: not_applied

          • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

            Why the reprice was not applied.

            A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

            • "body_mismatch"

            • "continuation_excluded"

            • "continuation_only"

            • "expired"

            • "invalid_target_model"

            • "not_enabled"

            • "reprice_unavailable"

            • "temporarily_unavailable"

            • "variant_fields_present"

            • "wrong_organization"

            • "wrong_platform"

            • "wrong_workspace"

          • remove_to_redeem: optional array of string or null

            Request fields to remove before retrying, so the retry can redeem this token.

            Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

    • inference_geo: string or null

      The geographic region where inference was performed for this request.

    • input_tokens: number

      The number of input tokens which were used.

      minimum: 0

    • iterations: BetaIterationsUsage or null

      Per-iteration token usage breakdown.

      Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

      • Determine which iterations exceeded long context thresholds (>=200k tokens)
      • Calculate the context window size from the last message entry
      • Understand token accumulation across server-side tool use loops

      A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

      • BetaMessageIterationUsage object

        Token usage for a sampling iteration.

        • type: "message"

          Usage for a sampling iteration

          default: message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaCompactionIterationUsage object

        Token usage for a compaction iteration.

        • type: "compaction"

          Usage for a compaction iteration

          default: compaction

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaAdvisorMessageIterationUsage object

        Token usage for an advisor sub-inference iteration.

        • type: "advisor_message"

          Usage for an advisor sub-inference iteration

          default: advisor_message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaFallbackMessageIterationUsage object

        Token usage for the fallback-model attempt of a server-side fallback request.

        Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

        • type: "fallback_message"

          Usage for the fallback-model attempt that served the response

          default: fallback_message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

    • output_tokens: number

      The number of output tokens which were used.

      minimum: 0

    • output_tokens_details: BetaOutputTokensDetails or null

      Breakdown of output tokens by category.

      output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

      • thinking_tokens: number

        Number of output tokens the model generated as internal reasoning, including the thinking-block delimiter tokens.

        Reflects the raw reasoning the model produced, not the (possibly shorter) summarized thinking text returned in the response body. Computed by re-tokenizing the raw reasoning text, so it may differ from the model's exact generation count by a small number of tokens. Always ≤ output_tokens; output_tokens - thinking_tokens approximates the non-reasoning output.

        default: 0, minimum: 0

    • server_tool_use: BetaServerToolUsage or null

      The number of server tool requests.

      • web_fetch_requests: number

        The number of web fetch tool requests.

        default: 0, minimum: 0

      • web_search_requests: number

        The number of web search tool requests.

        default: 0, minimum: 0

    • service_tier: "standard" or "priority" or "batch" or null

      If the request used the priority, standard, or batch tier.

      • "standard"

      • "priority"

      • "batch"

    • speed: "standard" or "fast" or null

      Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

      • "standard"

      • "fast"

  • input_transformations: optional array of BetaThinkingDroppedInputTransformation or null

    Changes the API made to the request's input before showing it to the model: one entry per change, in request order. Today the only entry type is thinking_dropped — a thinking, redacted_thinking or connector_text block from the request's messages that was removed from the prompt instead of being shown to the model because it failed a binding check. More entry types may be added over time; ignore types you do not recognize.

    Requires anthropic-beta: thinking-binding-controls-2026-08-01. Present on every such response from a model that supports extended thinking, as [] when nothing was changed; without the beta, blocks are removed all the same but nothing is reported. Removed blocks contribute nothing to usage.input_tokens. When streaming, the array is final in message_start; the final message_delta event carries it only when a server-side model fallback happened mid-stream, in which case it holds the serving model's entries and replaces the one in message_start.

    • type: "thinking_dropped"

      Always thinking_dropped for this entry type.

      default: thinking_dropped

    • path: string

      Where the removed block was in your request, as messages.\{i\}.content.\{j\}: i indexes the messages array you sent and j that message's content array — the same form error messages use.

    • reason: "model_binding_mismatch" or "prefix_binding_mismatch" or "organization_binding_mismatch" or "end_user_binding_mismatch"

      Which binding check removed the block: model_binding_mismatch — it was created by a model whose reasoning the requested model may not read; prefix_binding_mismatch — the conversation before it differs from the conversation it was created in (the rest of that turn's consecutive thinking blocks are removed with it, each with this reason); organization_binding_mismatch — it was created under a different organization (an Anthropic organization, AWS account or Google Cloud project) and this organization is not one of its additional organizations; end_user_binding_mismatch — it was created for a different end user, or was removed by the consumer-organization binding. A block that would fail several checks reports one reason, in this order of precedence: organization_binding_mismatch, end_user_binding_mismatch, model_binding_mismatch, prefix_binding_mismatch.

      • "model_binding_mismatch"

      • "prefix_binding_mismatch"

      • "organization_binding_mismatch"

      • "end_user_binding_mismatch"

• BetaRawMessageStreamEvent = BetaRawMessageStartEvent or BetaRawMessageDeltaEvent or BetaRawMessageStopEvent or 3 more

  • BetaRawMessageStartEvent object

    • type: "message_start"

      default: message_start

    • message: BetaMessage

  • BetaRawMessageDeltaEvent object

    • type: "message_delta"

      default: message_delta

    • context_management: BetaContextManagementResponse or null

      Information about context management strategies applied during the request

    • delta: object

      • container: BetaContainer or null

        Information about the container used in the request (for the code execution tool)

      • stop_details: BetaRefusalStopDetails or null

        Structured information about a refusal.

      • stop_reason: BetaStopReason or null

      • stop_sequence: string or null

    • usage: BetaMessageDeltaUsage

      Billing and rate-limit usage.

      Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

      Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in usage will not match one-to-one with the exact visible content of an API request or response.

      For example, output_tokens will be non-zero, even for an empty string response from Claude.

      Total input tokens in a request is the summation of input_tokens, cache_creation_input_tokens, and cache_read_input_tokens.

      • cache_creation_input_tokens: number or null

        The cumulative number of input tokens used to create the cache entry.

        minimum: 0

      • cache_read_input_tokens: number or null

        The cumulative number of input tokens read from the cache.

        minimum: 0

      • fallback_credit: BetaFallbackCreditUsage or null

        Outcome of the fallback_credit_token presented on this request.

      • input_tokens: number or null

        The cumulative number of input tokens which were used.

        minimum: 0

      • iterations: BetaIterationsUsage or null

        Per-iteration token usage breakdown.

        Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

        • Determine which iterations exceeded long context thresholds (>=200k tokens)
        • Calculate the context window size from the last message entry
        • Understand token accumulation across server-side tool use loops

        A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

      • output_tokens: number

        The cumulative number of output tokens which were used.

      • output_tokens_details: BetaOutputTokensDetails or null

        Breakdown of output tokens by category.

        output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

      • server_tool_use: BetaServerToolUsage or null

        The number of server tool requests.

    • input_transformations: optional array of BetaThinkingDroppedInputTransformation or null

      Changes the API made to the request's input before showing it to the model: one entry per change, in request order. Today the only entry type is thinking_dropped — a thinking, redacted_thinking or connector_text block from the request's messages that was removed from the prompt instead of being shown to the model because it failed a binding check. More entry types may be added over time; ignore types you do not recognize.

      Requires anthropic-beta: thinking-binding-controls-2026-08-01. Present on every such response from a model that supports extended thinking, as [] when nothing was changed; without the beta, blocks are removed all the same but nothing is reported. Removed blocks contribute nothing to usage.input_tokens. When streaming, the array is final in message_start; the final message_delta event carries it only when a server-side model fallback happened mid-stream, in which case it holds the serving model's entries and replaces the one in message_start.

      • type: "thinking_dropped"

        Always thinking_dropped for this entry type.

        default: thinking_dropped

      • path: string

        Where the removed block was in your request, as messages.\{i\}.content.\{j\}: i indexes the messages array you sent and j that message's content array — the same form error messages use.

      • reason: "model_binding_mismatch" or "prefix_binding_mismatch" or "organization_binding_mismatch" or "end_user_binding_mismatch"

        Which binding check removed the block: model_binding_mismatch — it was created by a model whose reasoning the requested model may not read; prefix_binding_mismatch — the conversation before it differs from the conversation it was created in (the rest of that turn's consecutive thinking blocks are removed with it, each with this reason); organization_binding_mismatch — it was created under a different organization (an Anthropic organization, AWS account or Google Cloud project) and this organization is not one of its additional organizations; end_user_binding_mismatch — it was created for a different end user, or was removed by the consumer-organization binding. A block that would fail several checks reports one reason, in this order of precedence: organization_binding_mismatch, end_user_binding_mismatch, model_binding_mismatch, prefix_binding_mismatch.

  • BetaRawMessageStopEvent object

    • type: "message_stop"

      default: message_stop

  • BetaRawContentBlockStartEvent object

    • type: "content_block_start"

      default: content_block_start

    • content_block: BetaTextBlock or BetaThinkingBlock or BetaRedactedThinkingBlock or 14 more

      Response model for a file uploaded to the container.

      • BetaTextBlock object

      • BetaThinkingBlock object

      • BetaRedactedThinkingBlock object

      • BetaToolUseBlock object

      • BetaServerToolUseBlock object

      • BetaWebSearchToolResultBlock object

      • BetaWebFetchToolResultBlock object

      • BetaAdvisorToolResultBlock object

      • BetaCodeExecutionToolResultBlock object

      • BetaBashCodeExecutionToolResultBlock object

      • BetaTextEditorCodeExecutionToolResultBlock object

      • BetaToolSearchToolResultBlock object

      • BetaMCPToolUseBlock object

      • BetaMCPToolResultBlock object

      • BetaContainerUploadBlock object

        Response model for a file uploaded to the container.

      • BetaCompactionBlock object

        A compaction block returned when autocompact is triggered.

        When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

      • BetaFallbackBlock object

        Marks the point in content where one model's output gives way to the next.

        One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

        The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

    • index: number

  • BetaRawContentBlockDeltaEvent object

    • type: "content_block_delta"

      default: content_block_delta

    • delta: BetaRawContentBlockDelta

      • BetaTextDelta object

        • type: "text_delta"

          default: text_delta

        • text: string

      • BetaInputJSONDelta object

        • type: "input_json_delta"

          default: input_json_delta

        • partial_json: string

      • BetaCitationsDelta object

        • type: "citations_delta"

          default: citations_delta

        • citation: BetaCitationCharLocation or BetaCitationPageLocation or BetaCitationContentBlockLocation or 2 more

          • BetaCitationCharLocation object

          • BetaCitationPageLocation object

          • BetaCitationContentBlockLocation object

          • BetaCitationsWebSearchResultLocation object

          • BetaCitationSearchResultLocation object

      • BetaThinkingDelta object

        • type: "thinking_delta"

          default: thinking_delta

        • estimated_tokens: number or null

          Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the thinking-token-count-2026-05-13 beta is set; null unless thinking.display resolves to "omitted" and a count is due this frame. Sum the increments across thinking_delta frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; usage.output_tokens remains authoritative.

        • thinking: string

          The incremental thinking text for this content block. Concatenate the thinking values of successive thinking_delta events to assemble the block's full thinking value.

      • BetaSignatureDelta object

        • type: "signature_delta"

          default: signature_delta

        • signature: string

          The signature for this thinking block: an opaque value used to verify that the block was generated by Claude when it is passed back to the API. Delivered in a signature_delta event just before the block's content_block_stop event.

      • BetaCompactionContentBlockDelta object

        • type: "compaction_delta"

          default: compaction_delta

        • content: string or null

        • encrypted_content: string or null

          Opaque metadata from prior compaction, to be round-tripped verbatim

    • index: number

  • BetaRawContentBlockStopEvent object

    • type: "content_block_stop"

      default: content_block_stop

    • index: number

Example

curl https://api.anthropic.com/v1/messages \
    -H 'Content-Type: application/json' \
    -H 'anthropic-version: 2023-06-01' \
    -H "X-Api-Key: $ANTHROPIC_API_KEY" \
    --max-time 600 \
    -d '{
          "max_tokens": 1024,
          "messages": [
            {
              "content": "Hello, world",
              "role": "user"
            }
          ],
          "model": "claude-opus-5",
          "stream": false,
          "system": [
            {
              "text": "Today'\''s date is 2024-06-01.",
              "type": "text"
            }
          ],
          "temperature": 1,
          "thinking": {
            "type": "adaptive"
          },
          "tools": [
            {
              "input_schema": {
                "type": "object",
                "properties": {
                  "location": "bar",
                  "unit": "bar"
                },
                "required": [
                  "location"
                ]
              },
              "name": "name"
            }
          ],
          "top_k": 5,
          "top_p": 0.7
        }'

Response (200)

{
  "id": "msg_013Zva2CMHLNnXjNJJKqJ2EF",
  "container": {
    "id": "container_011CpZohnwH4vuy7gazohgSP",
    "expires_at": "2019-12-27T18:11:19.117Z",
    "skills": [
      {
        "skill_id": "pdf",
        "type": "anthropic",
        "version": "latest"
      }
    ]
  },
  "content": [
    {
      "citations": [
        {
          "cited_text": "The grass is green. The sky is blue.",
          "document_index": 0,
          "document_title": "My Document",
          "end_char_index": 0,
          "file_id": "file_011CNha8iCJcU1wXNR6q4V8w",
          "start_char_index": 0,
          "type": "char_location"
        }
      ],
      "text": "Hi! My name is Claude.",
      "type": "text"
    }
  ],
  "context_management": {
    "applied_edits": [
      {
        "cleared_input_tokens": 0,
        "cleared_tool_uses": 0,
        "type": "clear_tool_uses_20250919"
      }
    ]
  },
  "diagnostics": {
    "cache_miss_reason": {
      "cache_missed_input_tokens": 0,
      "type": "model_changed"
    }
  },
  "model": "claude-opus-5",
  "role": "assistant",
  "stop_details": {
    "category": "cyber",
    "explanation": "This request was declined because it conflicts with Anthropic's Usage Policy.",
    "fallback_credit_token": "QW50aHJvcGljL0NsYXVkZQ==",
    "fallback_has_prefill_claim": true,
    "recommended_model": "claude-opus-4-8",
    "type": "refusal"
  },
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "type": "message",
  "usage": {
    "cache_creation": {
      "ephemeral_1h_input_tokens": 0,
      "ephemeral_5m_input_tokens": 0
    },
    "cache_creation_input_tokens": 2051,
    "cache_read_input_tokens": 2051,
    "fallback_credit": {
      "status": {
        "type": "redeemed"
      }
    },
    "inference_geo": "global",
    "input_tokens": 2095,
    "iterations": [
      {
        "cache_creation": {
          "ephemeral_1h_input_tokens": 0,
          "ephemeral_5m_input_tokens": 0
        },
        "cache_creation_input_tokens": 0,
        "cache_read_input_tokens": 0,
        "input_tokens": 0,
        "model": "claude-fable-5-1",
        "output_tokens": 0,
        "type": "message"
      }
    ],
    "output_tokens": 503,
    "output_tokens_details": {
      "thinking_tokens": 0
    },
    "server_tool_use": {
      "web_fetch_requests": 2,
      "web_search_requests": 0
    },
    "service_tier": "standard",
    "speed": "standard"
  },
  "input_transformations": [
    {
      "path": "path",
      "reason": "model_binding_mismatch",
      "type": "thinking_dropped"
    }
  ]
}

Count tokens in a Message

POST /v1/messages/count_tokens

Count the number of tokens in a Message.

The Token Count API can be used to count the number of tokens in a Message, including tools, images, and documents, without creating it.

Learn more about token counting in our user guide

Headers

• "anthropic-beta": optional array of AnthropicBeta

  Optional header to specify the beta version(s) you want to use.

  • string

  • "message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 42 more

    • "message-batches-2024-09-24"

    • "prompt-caching-2024-07-31"

    • "computer-use-2024-10-22"

    • "computer-use-2025-01-24"

    • "pdfs-2024-09-25"

    • "token-counting-2024-11-01"

    • "token-efficient-tools-2025-02-19"

    • "output-128k-2025-02-19"

    • "files-api-2025-04-14"

    • "mcp-client-2025-04-04"

    • "mcp-client-2025-11-20"

    • "dev-full-thinking-2025-05-14"

    • "interleaved-thinking-2025-05-14"

    • "code-execution-2025-05-22"

    • "extended-cache-ttl-2025-04-11"

    • "context-1m-2025-08-07"

    • "context-management-2025-06-27"

    • "model-context-window-exceeded-2025-08-26"

    • "skills-2025-10-02"

    • "fast-mode-2026-02-01"

    • "output-300k-2026-03-24"

    • "user-profiles-2026-03-24"

    • "user-profiles-2026-08-18"

    • "user-profiles-2026-09-04"

    • "advisor-tool-2026-03-01"

    • "managed-agents-2026-04-01"

    • "cache-diagnosis-2026-04-07"

    • "dreaming-2026-04-21"

    • "thinking-token-count-2026-05-13"

    • "server-side-fallback-2026-06-01"

    • "server-side-fallback-2026-07-01"

    • "fallback-credit-2026-06-01"

    • "fallback-credit-2026-07-01"

    • "agent-memory-2026-07-22"

    • "mid-conversation-tool-changes-2026-07-01"

    • "compact-2026-01-12"

    • "computer-use-2025-11-24"

    • "mcp-tunnels-2026-06-22"

    • "structured-outputs-2025-11-13"

    • "task-budgets-2026-03-13"

    • "thinking-display-updates-2026-08-18"

    • "ce-user-management-2026-07-13"

    • "mid-conversation-output-config-2026-07-01"

    • "thinking-binding-controls-2026-08-01"

    • "mid-conversation-system-clear-at-2026-08-21"

• "anthropic-user-profile-id": optional string

  The user profile ID to attribute this request to. Use when acting on behalf of a party other than your organization. Requires the user-profiles beta header.

• "anthropic-workspace-id": optional string

Body parameters

• messages: array of BetaMessageParam

  Input messages.

  Our models are trained to operate on alternating user and assistant conversational turns. When creating a new Message, you specify the prior conversational turns with the messages parameter, and the model then generates the next Message in the conversation. Consecutive user or assistant turns in your request will be combined into a single turn.

  Each input message must be an object with a role and content. You can specify a single user-role message, or you can include multiple user and assistant messages.

  If the final message uses the assistant role, the response content will continue immediately from the content in that message. This can be used to constrain part of the model's response.

  Example with a single user message:

  [{"role": "user", "content": "Hello, Claude"}]

  Example with multiple conversational turns:

  [
    {"role": "user", "content": "Hello there."},
    {"role": "assistant", "content": "Hi, I'm Claude. How can I help you?"},
    {"role": "user", "content": "Can you explain LLMs in plain English?"},
  ]

  Example with a partially-filled response from Claude:

  [
    {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
    {"role": "assistant", "content": "The best answer is ("},
  ]

  Each input message content may be either a single string or an array of content blocks, where each block has a specific type. Using a string for content is shorthand for an array of one content block of type "text". The following input messages are equivalent:

  {"role": "user", "content": "Hello, Claude"}

  {"role": "user", "content": [{"type": "text", "text": "Hello, Claude"}]}

  See input examples.

  Note that if you want to include a system prompt, you can use the top-level system parameter — there is no "system" role for input messages in the Messages API.

  There is a limit of 100,000 messages in a single request.

  • content: string or array of BetaContentBlockParam

    • string

    • array of BetaContentBlockParam

      • BetaTextBlockParam object

        • type: "text"

        • text: string

          minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

          • type: "ephemeral"

          • ttl: optional "5m" or "1h"

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            • 5m: 5 minutes
            • 1h: 1 hour

            Defaults to 5m. See prompt caching pricing for details.

            • "5m"

            • "1h"

        • citations: optional array of BetaTextCitationParam or null

          • BetaCitationCharLocationParam object

            • type: "char_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_char_index: number

            • start_char_index: number

              minimum: 0

          • BetaCitationPageLocationParam object

            • type: "page_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_page_number: number

            • start_page_number: number

              minimum: 1

          • BetaCitationContentBlockLocationParam object

            • type: "content_block_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

          • BetaCitationWebSearchResultLocationParam object

            • type: "web_search_result_location"

            • cited_text: string

            • encrypted_index: string

            • title: string or null

              maxLength: 512, minLength: 1

            • url: string

              minLength: 1

          • BetaCitationSearchResultLocationParam object

            • type: "search_result_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • search_result_index: number

              0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from document_index; server-side web search results are not included in this count.

              minimum: 0

            • source: string

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

            • title: string or null

      • BetaImageBlockParam object

        • type: "image"

        • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

          • BetaBase64ImageSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

              • "image/jpeg"

              • "image/png"

              • "image/gif"

              • "image/webp"

          • BetaURLImageSource object

            • type: "url"

            • url: string

          • BetaFileImageSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • transformations: optional BetaImageTransformationsParam or null

          Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

          • oversized_image: optional "downsize" or "error"

            What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

            • "downsize"

            • "error"

      • BetaRequestDocumentBlock object

        • type: "document"

        • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

          • BetaBase64PDFSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "application/pdf"

          • BetaPlainTextSource object

            • type: "text"

            • data: string

            • media_type: "text/plain"

          • BetaContentBlockSource object

            • type: "content"

            • content: string or array of BetaContentBlockSourceContent

              • string

              • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

                • BetaTextBlockParam object

                • BetaImageBlockParam object

          • BetaURLPDFSource object

            • type: "url"

            • url: string

          • BetaFileDocumentSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

          • enabled: optional boolean

        • context: optional string or null

          minLength: 1

        • title: optional string or null

          maxLength: 500, minLength: 1

      • BetaSearchResultBlockParam object

        • type: "search_result"

        • content: array of BetaTextBlockParam

          • type: "text"

          • text: string

            minLength: 1

          • cache_control: optional BetaCacheControlEphemeral or null

            Create a cache control breakpoint at this content block.

          • citations: optional array of BetaTextCitationParam or null

        • source: string

        • title: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam

      • BetaThinkingBlockParam object

        • type: "thinking"

        • signature: string

          The signature value of this thinking block, exactly as returned by the API in a previous response. Used to verify that the block was generated by Claude.

          Thinking blocks must be passed back unmodified and in their original order; a modified block results in a 400 invalid_request_error.

        • thinking: string

          The thinking text of this block as returned by the API.

      • BetaRedactedThinkingBlockParam object

        • type: "redacted_thinking"

        • data: string

          The data value of this redacted thinking block, exactly as returned by the API in a previous response. Opaque and encrypted; pass it back unchanged.

      • BetaToolUseBlockParam object

        • type: "tool_use"

        • id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • input: map[unknown]

        • name: string

          maxLength: 200, minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

            • type: "direct"

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

            • type: "code_execution_20250825"

            • tool_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

          • BetaServerToolCaller20260120 object

            • type: "code_execution_20260120"

            • tool_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • toolset_name: optional string or null

          For a toolset member tool_use, the toolset family this member belongs to.

          maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

      • BetaToolResultBlockParam object

        • type: "tool_result"

        • tool_use_id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

          • string

          • array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

            • BetaTextBlockParam object

            • BetaImageBlockParam object

            • BetaSearchResultBlockParam object

            • BetaRequestDocumentBlock object

            • BetaToolReferenceBlockParam object

              Tool reference block that can be included in tool_result content.

              • type: "tool_reference"

              • tool_name: string

                maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

            • BetaBrowserStateBlockParam object

              The caller's browser state after a browser toolset member call — the full inventory of open tabs, which tab is active, and any side effects (tabs opened, download state changes) the call produced.

              At most one per tool_result, only on a non-error result answering a browser toolset member tool_use. The server renders the model-visible text from it; the model never sees the raw fields.

              • type: "browser_state"

              • tabs: array of BetaBrowserStateTabEntry

                All tabs open in the browser after this call — the full inventory, not a delta. May be empty. Whenever non-empty, exactly one entry carries active: true.

                maxItems: 100

                • tab_id: string

                  The caller-assigned identifier for this tab, unique within the inventory.

                  maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • title: string

                  The title of the page the tab is showing. May be empty.

                  maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • url: string

                  The URL of the page the tab is showing. May be empty.

                  maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • active: optional boolean

                  Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

              • state_changes: optional array of BetaBrowserStateChange or null

                Tabs opened and download state changes during this call. "Nothing to report" is expressed by omitting the field, never by an empty list.

                maxItems: 200, minItems: 1

                • BetaBrowserStateChangeTabOpened object

                  A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

                  Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

                  • type: "tab_opened"

                  • tab_id: string

                    The tab_id of the opened tab, present in tabs.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • BetaBrowserStateChangeDownloadStarted object

                  A file download that started during this call.

                  • type: "download_started"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • BetaBrowserStateChangeDownloadCompleted object

                  A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

                  • type: "download_completed"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • path: optional string or null

                    Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

                    pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

                  • size_bytes: optional number or null

                    The completed download's size.

                    minimum: 0

                • BetaBrowserStateChangeDownloadFailed object

                  A file download that failed — or was cancelled — during this call.

                  • type: "download_failed"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • error: optional string or null

                    The failure or cancellation detail, when known.

                    pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

        • is_error: optional boolean

        • toolset_name: optional string or null

          For a toolset member tool_result, the toolset family of the paired tool_use.

          maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

      • BetaServerToolUseBlockParam object

        • type: "server_tool_use"

        • id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • input: map[unknown]

        • name: "advisor" or "web_search" or "web_fetch" or 5 more

          • "advisor"

          • "web_search"

          • "web_fetch"

          • "code_execution"

          • "bash_code_execution"

          • "text_editor_code_execution"

          • "tool_search_tool_regex"

          • "tool_search_tool_bm25"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaWebSearchToolResultBlockParam object

        • type: "web_search_tool_result"

        • content: BetaWebSearchToolResultBlockParamContent

          • ResultBlock = array of BetaWebSearchResultBlockParam

            • type: "web_search_result"

            • encrypted_content: string

            • title: string

            • url: string

            • page_age: optional string or null

          • BetaWebSearchToolRequestError object

            • type: "web_search_tool_result_error"

            • error_code: BetaWebSearchToolResultErrorCode

              • "invalid_tool_input"

              • "unavailable"

              • "max_uses_exceeded"

              • "too_many_requests"

              • "query_too_long"

              • "request_too_large"

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaWebFetchToolResultBlockParam object

        • type: "web_fetch_tool_result"

        • content: BetaWebFetchToolResultErrorBlockParam or BetaWebFetchBlockParam

          • BetaWebFetchToolResultErrorBlockParam object

            • type: "web_fetch_tool_result_error"

            • error_code: BetaWebFetchToolResultErrorCode

              • "invalid_tool_input"

              • "url_too_long"

              • "url_not_allowed"

              • "url_not_in_prior_context"

              • "url_not_accessible"

              • "unsupported_content_type"

              • "too_many_requests"

              • "max_uses_exceeded"

              • "unavailable"

              • "content_too_large"

          • BetaWebFetchBlockParam object

            • type: "web_fetch_result"

            • content: BetaRequestDocumentBlock

            • url: string

              Fetched content URL

            • retrieved_at: optional string or null

              ISO 8601 timestamp when the content was retrieved

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaAdvisorToolResultBlockParam object

        • type: "advisor_tool_result"

        • content: BetaAdvisorToolResultErrorParam or BetaAdvisorResultBlockParam or BetaAdvisorRedactedResultBlockParam

          • BetaAdvisorToolResultErrorParam object

            • type: "advisor_tool_result_error"

            • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

              • "max_uses_exceeded"

              • "prompt_too_long"

              • "too_many_requests"

              • "overloaded"

              • "unavailable"

              • "execution_time_exceeded"

              • "model_not_found"

          • BetaAdvisorResultBlockParam object

            • type: "advisor_result"

            • text: string

            • stop_reason: optional string or null

          • BetaAdvisorRedactedResultBlockParam object

            • type: "advisor_redacted_result"

            • encrypted_content: string

              Opaque blob produced by a prior response; must be round-tripped verbatim.

            • stop_reason: optional string or null

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaCodeExecutionToolResultBlockParam object

        • type: "code_execution_tool_result"

        • content: BetaCodeExecutionToolResultBlockParamContent

          Code execution result with encrypted stdout for PFC + web_search results.

          • BetaCodeExecutionToolResultErrorParam object

            • type: "code_execution_tool_result_error"

            • error_code: BetaCodeExecutionToolResultErrorCode

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

          • BetaCodeExecutionResultBlockParam object

            • type: "code_execution_result"

            • content: array of BetaCodeExecutionOutputBlockParam

              • type: "code_execution_output"

              • file_id: string

            • return_code: number

            • stderr: string

            • stdout: string

          • BetaEncryptedCodeExecutionResultBlockParam object

            Code execution result with encrypted stdout for PFC + web_search results.

            • type: "encrypted_code_execution_result"

            • content: array of BetaCodeExecutionOutputBlockParam

              • type: "code_execution_output"

              • file_id: string

            • encrypted_stdout: string

            • return_code: number

            • stderr: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaBashCodeExecutionToolResultBlockParam object

        • type: "bash_code_execution_tool_result"

        • content: BetaBashCodeExecutionToolResultErrorParam or BetaBashCodeExecutionResultBlockParam

          • BetaBashCodeExecutionToolResultErrorParam object

            • type: "bash_code_execution_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

              • "output_file_too_large"

          • BetaBashCodeExecutionResultBlockParam object

            • type: "bash_code_execution_result"

            • content: array of BetaBashCodeExecutionOutputBlockParam

              • type: "bash_code_execution_output"

              • file_id: string

            • return_code: number

            • stderr: string

            • stdout: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaTextEditorCodeExecutionToolResultBlockParam object

        • type: "text_editor_code_execution_tool_result"

        • content: BetaTextEditorCodeExecutionToolResultErrorParam or BetaTextEditorCodeExecutionViewResultBlockParam or BetaTextEditorCodeExecutionCreateResultBlockParam or BetaTextEditorCodeExecutionStrReplaceResultBlockParam

          • BetaTextEditorCodeExecutionToolResultErrorParam object

            • type: "text_editor_code_execution_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

              • "file_not_found"

            • error_message: optional string or null

          • BetaTextEditorCodeExecutionViewResultBlockParam object

            • type: "text_editor_code_execution_view_result"

            • content: string

            • file_type: "text" or "image" or "pdf"

              • "text"

              • "image"

              • "pdf"

            • num_lines: optional number or null

            • start_line: optional number or null

            • total_lines: optional number or null

          • BetaTextEditorCodeExecutionCreateResultBlockParam object

            • type: "text_editor_code_execution_create_result"

            • is_file_update: boolean

          • BetaTextEditorCodeExecutionStrReplaceResultBlockParam object

            • type: "text_editor_code_execution_str_replace_result"

            • lines: optional array of string or null

            • new_lines: optional number or null

            • new_start: optional number or null

            • old_lines: optional number or null

            • old_start: optional number or null

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaToolSearchToolResultBlockParam object

        • type: "tool_search_tool_result"

        • content: BetaToolSearchToolResultErrorParam or BetaToolSearchToolSearchResultBlockParam

          • BetaToolSearchToolResultErrorParam object

            • type: "tool_search_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

            • error_message: optional string or null

          • BetaToolSearchToolSearchResultBlockParam object

            • type: "tool_search_tool_search_result"

            • tool_references: array of BetaToolReferenceBlockParam

              • type: "tool_reference"

              • tool_name: string

                maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaMCPToolUseBlockParam object

        • type: "mcp_tool_use"

        • id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • input: map[unknown]

        • name: string

        • server_name: string

          The name of the MCP server

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaRequestMCPToolResultBlockParam object

        • type: "mcp_tool_result"

        • tool_use_id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or array of BetaTextBlockParam

          • string

          • BetaMCPToolResultBlockParamContent = array of BetaTextBlockParam

            • type: "text"

            • text: string

              minLength: 1

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • citations: optional array of BetaTextCitationParam or null

        • is_error: optional boolean

      • BetaContainerUploadBlockParam object

        A content block that represents a file to be uploaded to the container Files uploaded via this block will be available in the container's input directory.

        • type: "container_upload"

        • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaCompactionBlockParam object

        A compaction block containing summary of previous context.

        Users should round-trip these blocks from responses to subsequent requests to maintain context across compaction boundaries.

        When content is None, the block represents a failed compaction. The server treats these as no-ops. Empty string content is not allowed.

        • type: "compaction"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or null

          Summary of previously compacted content, or null if compaction failed

        • encrypted_content: optional string or null

          Opaque metadata from prior compaction, to be round-tripped verbatim

      • BetaRequestToolAdditionBlock object

        Mid-conversation directive to surface a declared tool.

        tool references a tool (or MCP toolset) by name from the request's tools; it is offered to the model from this point in the conversation onward.

        • type: "tool_addition"

        • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

          Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeToolReference object

            Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

            • type: "tool_reference"

            • name: string

              pattern: ^[a-zA-Z0-9_-]{1,128}$

          • BetaToolChangeMCPToolReference object

            Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

            • type: "mcp_tool_reference"

            • name: string

            • server_name: string

          • BetaToolChangeMCPToolsetReference object

            Reference to every tool in the named MCP server's toolset.

            • type: "mcp_toolset_reference"

            • server_name: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaRequestToolRemovalBlock object

        Mid-conversation directive to withdraw a tool.

        tool references a tool (or MCP toolset) by name from the request's tools; it is no longer offered to the model from this point in the conversation onward.

        • type: "tool_removal"

        • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

          Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeToolReference object

            Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeMCPToolReference object

            Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

          • BetaToolChangeMCPToolsetReference object

            Reference to every tool in the named MCP server's toolset.

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaFallbackBlockParam object

        A fallback block echoed back from a prior response.

        Accepted in messages[].content and not rendered into the prompt; not validated against the request's fallbacks chain or top-level model.

        Echo the assistant turn back verbatim, including this block in its original position. The block marks the boundary between content produced before and after a fallback hop, and the server relies on that boundary to validate the turn: when thinking runs flank the boundary, omitting the block merges them into one span the server cannot validate (the request is rejected), and moving it into the middle of a single run is likewise rejected; between non-thinking blocks the block's placement has no validation effect.

        • type: "fallback"

        • from: BetaFallbackInfoParam

          Identifies one hop of a fallback transition.

          • model: Model

            The model that will complete your prompt.

            See models for additional details and options.

            • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

              The model that will complete your prompt.

              See models for additional details and options.

              • "claude-fable-5-1"

                Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

              • "claude-mythos-5-1"

                Our most capable model for cybersecurity and biology research, available through trusted access programs

              • "claude-sonnet-5"

                High-performance model for coding and agents

              • "claude-fable-5"

                Next generation of intelligence for the hardest knowledge work and coding problems

              • "claude-mythos-5"

                Most capable model for cybersecurity and biology research

              • "claude-opus-5"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-8"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-7"

                Powerful intelligence for long-running agents and coding

              • "claude-mythos-preview"

                New class of intelligence, strongest in coding and cybersecurity

              • "claude-opus-4-6"

                Powerful intelligence for long-running agents and coding

              • "claude-sonnet-4-6"

                Best combination of speed and intelligence

              • "claude-haiku-4-5"

                Fastest model with near-frontier intelligence

              • "claude-haiku-4-5-20251001"

                Fastest model with near-frontier intelligence

              • "claude-opus-4-5"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-5-20251101"

                Powerful intelligence for long-running agents and coding

              • "claude-sonnet-4-5"

                High-performance model for agents and coding

              • "claude-sonnet-4-5-20250929"

                High-performance model for agents and coding

            • string

        • to: BetaFallbackInfoParam

          Identifies one hop of a fallback transition.

        • trigger: optional unknown

          The response block's trigger, echoed verbatim. Accepted and ignored by the server; any object or null is allowed.

  • role: "user" or "assistant" or "system"

    • "user"

    • "assistant"

    • "system"

  • clear_at: optional "next_user_message" or "never" or null

    How long this system message's text stays in front of the model. "never" (the default) renders it on every request that includes it. "next_user_message" renders it only for the user turn it follows: once a later role: "user" message exists in messages the message stays in the array (send it unchanged) but is no longer shown to the model. Only permitted on role: "system" messages.

    • "next_user_message"

    • "never"

  • output_config: optional BetaSystemMessageOutputConfig or null

    Per-message output configuration on a role:"system" input message.

    Fields here apply per-turn; format remains top-level only. An empty \{\} is accepted on a message that carries content; a message with neither content nor output_config fields is rejected.

    • effort: optional "low" or "medium" or "high" or 2 more or null

      All possible effort levels.

      • "low"

      • "medium"

      • "high"

      • "xhigh"

      • "max"

• model: Model

  The model that will complete your prompt.

  See models for additional details and options.

• cache_control: optional BetaCacheControlEphemeral or null

  Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.

• context_management: optional BetaContextManagementConfig or null

  Context management configuration.

  This allows you to control how Claude manages context across multiple requests, such as whether to clear function results or not.

  • edits: optional array of BetaClearToolUses20250919Edit or BetaClearThinking20251015Edit or BetaCompact20260112Edit

    List of context management edits to apply

    minItems: 0

    • BetaClearToolUses20250919Edit object

      • type: "clear_tool_uses_20250919"

      • clear_at_least: optional BetaInputTokensClearAtLeast or null

        Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

        • type: "input_tokens"

        • value: number

          minimum: 0

      • clear_tool_inputs: optional boolean or array of string or null

        Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

        • boolean

        • array of string

      • exclude_tools: optional array of string or null

        Tool names whose uses are preserved from clearing

      • keep: optional BetaToolUsesKeep

        Number of tool uses to retain in the conversation

        • type: "tool_uses"

        • value: number

          minimum: 0

      • trigger: optional BetaInputTokensTrigger or BetaToolUsesTrigger

        Condition that triggers the context management strategy

        • BetaInputTokensTrigger object

          • type: "input_tokens"

          • value: number

            minimum: 1

        • BetaToolUsesTrigger object

          • type: "tool_uses"

          • value: number

            minimum: 1

    • BetaClearThinking20251015Edit object

      • type: "clear_thinking_20251015"

      • keep: optional BetaThinkingTurns or BetaAllThinkingTurns or "all"

        Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

        • BetaThinkingTurns object

          • type: "thinking_turns"

          • value: number

            minimum: 1

        • BetaAllThinkingTurns object

          • type: "all"

        • "all"

    • BetaCompact20260112Edit object

      Automatically compact older context when reaching the configured trigger threshold.

      • type: "compact_20260112"

      • instructions: optional string or null

        Additional instructions for summarization.

      • pause_after_compaction: optional boolean

        Whether to pause after compaction and return the compaction block to the user.

      • trigger: optional BetaInputTokensTrigger or null

        When to trigger compaction. Defaults to 150000 input tokens.

• mcp_servers: optional array of BetaRequestMCPServerURLDefinition

  MCP servers to be utilized in this request

  maxItems: 20

  • type: "url"

  • name: string

  • url: string

  • authorization_token: optional string or null

  • tool_configuration: optional BetaRequestMCPServerToolConfiguration or null

    • allowed_tools: optional array of string or null

    • enabled: optional boolean or null

• output_config: optional BetaOutputConfig

  Configuration options for the model's output, such as the output format.

  • effort: optional "low" or "medium" or "high" or 2 more or null

    All possible effort levels.

    • "low"

    • "medium"

    • "high"

    • "xhigh"

    • "max"

  • format: optional BetaJSONOutputFormat or null

    A schema to specify Claude's output format in responses. See structured outputs

    • type: "json_schema"

    • schema: map[unknown]

      The JSON schema of the format

  • task_budget: optional BetaTokenTaskBudget or null

    User-configurable total token budget across contexts.

    • type: "tokens"

      The budget type. Currently only 'tokens' is supported.

    • total: number

      Total token budget across all contexts in the session.

      minimum: 1024

    • remaining: optional number or null

      Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

      minimum: 0

• speed: optional "standard" or "fast" or null

  Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

  • "standard"

  • "fast"

• system: optional string or array of BetaTextBlockParam

  System prompt.

  A system prompt is a way of providing context and instructions to Claude, such as specifying a particular goal or role. See our guide to system prompts.

  • string

  • array of BetaTextBlockParam

    • type: "text"

    • text: string

      minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional array of BetaTextCitationParam or null

• thinking: optional BetaThinkingConfigParam

  Configuration for enabling Claude's extended thinking.

  When enabled, responses include thinking content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your max_tokens limit.

  See extended thinking for details.

  • BetaThinkingConfigEnabled object

    • type: "enabled"

    • budget_tokens: number

      Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

      Must be ≥1024 and less than max_tokens.

      See extended thinking for details.

      minimum: 1024

    • block_binding: optional BetaThinkingBlockBinding or null

      Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

      • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

        What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

        • "error"

        • "drop_block"

    • display: optional "summarized" or "omitted" or "updates" or null

      Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

      • "summarized"

      • "omitted"

      • "updates"

  • BetaThinkingConfigDisabled object

    • type: "disabled"

  • BetaThinkingConfigAdaptive object

    • type: "adaptive"

    • block_binding: optional BetaThinkingBlockBinding or null

      Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

    • display: optional "summarized" or "omitted" or "updates" or null

      Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

      • "summarized"

      • "omitted"

      • "updates"

• tool_choice: optional BetaToolChoice

  How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

  • BetaToolChoiceAuto object

    The model will automatically decide whether to use tools.

    • type: "auto"

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output at most one tool use.

  • BetaToolChoiceAny object

    The model will use any available tools.

    • type: "any"

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output exactly one tool use.

  • BetaToolChoiceTool object

    The model will use the specified tool with tool_choice.name.

    • type: "tool"

    • name: string

      The name of the tool to use.

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output exactly one tool use.

  • BetaToolChoiceNone object

    The model will not be allowed to use tools.

    • type: "none"

• tools: optional array of BetaTool or BetaToolBash20241022 or BetaToolBash20250124 or 25 more

  Definitions of tools that the model may use.

  If you include tools in your API request, the model may return tool_use content blocks that represent the model's use of those tools. You can then run those tools using the tool input generated by the model and then optionally return results back to the model using tool_result content blocks.

  There are two types of tools: client tools and server tools. The behavior described below applies to client tools. For server tools, see their individual documentation as each has its own behavior (e.g., the web search tool).

  Each tool definition includes:

  • name: Name of the tool.
  • description: Optional, but strongly-recommended description of the tool.
  • input_schema: JSON schema for the tool input shape that the model will produce in tool_use output content blocks.

  For example, if you defined tools as:

  [
    {
      "name": "get_stock_price",
      "description": "Get the current stock price for a given ticker symbol.",
      "input_schema": {
        "type": "object",
        "properties": {
          "ticker": {
            "type": "string",
            "description": "The stock ticker symbol, e.g. AAPL for Apple Inc."
          }
        },
        "required": ["ticker"]
      }
    }
  ]

  And then asked the model "What's the S&P 500 at today?", the model might produce tool_use content blocks in the response like this:

  [
    {
      "type": "tool_use",
      "id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "name": "get_stock_price",
      "input": { "ticker": "^GSPC" }
    }
  ]

  You might then run your get_stock_price tool with \{"ticker": "^GSPC"\} as an input, and return the following back to the model in a subsequent user message:

  [
    {
      "type": "tool_result",
      "tool_use_id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "content": "259.75 USD"
    }
  ]

  Tools can be used for workflows that include running client-side tools and functions, or more generally whenever you want the model to produce a particular JSON structure of output.

  See our guide for more details.

  • BetaTool object

    • type: optional "custom" or null

    • input_schema: object

      JSON schema for this tool's input.

      This defines the shape of the input that your tool accepts and that the model will produce.

      • type: "object"

      • properties: optional map[unknown] or null

      • required: optional array of string or null

    • name: string

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

      maxLength: 128, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,128}$

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • description: optional string

      Description of what this tool does.

      Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

    • eager_input_streaming: optional boolean or null

      Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolBash20241022 object

    • type: "bash_20241022"

    • name: "bash"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolBash20250124 object

    • type: "bash_20250124"

    • name: "bash"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20250522 object

    • type: "code_execution_20250522"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20250825 object

    • type: "code_execution_20250825"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20260120 object

    Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

    • type: "code_execution_20260120"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20260521 object

    Code execution tool with REPL state persistence.

    • type: "code_execution_20260521"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaBrowserToolset20260801 object

    The browser toolset: a single tools[] entry (carrying no name) that declares the browser tool family. The model is served the family's tool with any members disabled via configs removed from its schema.

    • type: "browser_toolset_20260801"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional BetaBrowserToolsetConfigs or null

      Per-member configuration for browser_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

      • type: optional BetaBrowserTypeConfig or null

        type's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • close_tab: optional BetaBrowserCloseTabConfig or null

        close_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • double_click: optional BetaBrowserDoubleClickConfig or null

        double_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • file_upload: optional BetaBrowserFileUploadConfig or null

        file_upload's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • find: optional BetaBrowserFindConfig or null

        find's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • form_input: optional BetaBrowserFormInputConfig or null

        form_input's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • get_page_text: optional BetaBrowserGetPageTextConfig or null

        get_page_text's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hold_key: optional BetaBrowserHoldKeyConfig or null

        hold_key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hover: optional BetaBrowserHoverConfig or null

        hover's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • javascript_exec: optional BetaBrowserJavascriptExecConfig or null

        javascript_exec's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • key: optional BetaBrowserKeyConfig or null

        key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click: optional BetaBrowserLeftClickConfig or null

        left_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click_drag: optional BetaBrowserLeftClickDragConfig or null

        left_click_drag's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_down: optional BetaBrowserLeftMouseDownConfig or null

        left_mouse_down's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_up: optional BetaBrowserLeftMouseUpConfig or null

        left_mouse_up's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • list_tabs: optional BetaBrowserListTabsConfig or null

        list_tabs's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • middle_click: optional BetaBrowserMiddleClickConfig or null

        middle_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • mouse_move: optional BetaBrowserMouseMoveConfig or null

        mouse_move's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • navigate: optional BetaBrowserNavigateConfig or null

        navigate's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • new_tab: optional BetaBrowserNewTabConfig or null

        new_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_console: optional BetaBrowserReadConsoleConfig or null

        read_console's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_network: optional BetaBrowserReadNetworkConfig or null

        read_network's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_page: optional BetaBrowserReadPageConfig or null

        read_page's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • right_click: optional BetaBrowserRightClickConfig or null

        right_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • screenshot: optional BetaBrowserScreenshotConfig or null

        screenshot's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll: optional BetaBrowserScrollConfig or null

        scroll's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll_to: optional BetaBrowserScrollToConfig or null

        scroll_to's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • switch_tab: optional BetaBrowserSwitchTabConfig or null

        switch_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • triple_click: optional BetaBrowserTripleClickConfig or null

        triple_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • wait: optional BetaBrowserWaitConfig or null

        wait's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • zoom: optional BetaBrowserZoomConfig or null

        zoom's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • BetaToolComputerUse20241022 object

    • type: "computer_20241022"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaMemoryTool20250818 object

    • type: "memory_20250818"

    • name: "memory"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolComputerUse20250124 object

    • type: "computer_20250124"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20241022 object

    • type: "text_editor_20241022"

    • name: "str_replace_editor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolComputerUse20251124 object

    • type: "computer_20251124"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • enable_zoom: optional boolean

      Whether to enable an action to take a zoomed-in screenshot of the screen.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaComputerToolset20260801 object

    The computer toolset: a single tools[] entry (carrying no name) that declares the computer tool family. The model is served the family's tool with any members disabled via configs removed from its schema. Every member is enabled by default, zoom included. The single-tool options display_number and enable_zoom are not fields of a toolset entry — it carries only type, configs, and cache_control; zoom is controlled via configs.zoom.enabled.

    • type: "computer_toolset_20260801"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional BetaComputerToolsetConfigs or null

      Per-member configuration for computer_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

      • type: optional BetaComputerTypeConfig or null

        type's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • cursor_position: optional BetaComputerCursorPositionConfig or null

        cursor_position's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • double_click: optional BetaComputerDoubleClickConfig or null

        double_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hold_key: optional BetaComputerHoldKeyConfig or null

        hold_key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • key: optional BetaComputerKeyConfig or null

        key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click: optional BetaComputerLeftClickConfig or null

        left_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click_drag: optional BetaComputerLeftClickDragConfig or null

        left_click_drag's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_down: optional BetaComputerLeftMouseDownConfig or null

        left_mouse_down's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_up: optional BetaComputerLeftMouseUpConfig or null

        left_mouse_up's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • middle_click: optional BetaComputerMiddleClickConfig or null

        middle_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • mouse_move: optional BetaComputerMouseMoveConfig or null

        mouse_move's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • right_click: optional BetaComputerRightClickConfig or null

        right_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • screenshot: optional BetaComputerScreenshotConfig or null

        screenshot's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll: optional BetaComputerScrollConfig or null

        scroll's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • triple_click: optional BetaComputerTripleClickConfig or null

        triple_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • wait: optional BetaComputerWaitConfig or null

        wait's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • zoom: optional BetaComputerZoomConfig or null

        zoom's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • BetaToolTextEditor20250124 object

    • type: "text_editor_20250124"

    • name: "str_replace_editor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20250429 object

    • type: "text_editor_20250429"

    • name: "str_replace_based_edit_tool"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20250728 object

    • type: "text_editor_20250728"

    • name: "str_replace_based_edit_tool"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • max_characters: optional number or null

      Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

      minimum: 1

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebSearchTool20250305 object

    • type: "web_search_20250305"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

      • type: "approximate"

      • city: optional string or null

        The city of the user.

        maxLength: 255, minLength: 1

      • country: optional string or null

        The two letter ISO country code of the user.

        maxLength: 2, minLength: 2

      • region: optional string or null

        The region of the user.

        maxLength: 255, minLength: 1

      • timezone: optional string or null

        The IANA timezone of the user.

        maxLength: 255, minLength: 1

  • BetaWebFetchTool20250910 object

    • type: "web_fetch_20250910"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebSearchTool20260209 object

    • type: "web_search_20260209"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

  • BetaWebFetchTool20260209 object

    • type: "web_fetch_20260209"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebFetchTool20260309 object

    Web fetch tool with use_cache parameter for bypassing cached content.

    • type: "web_fetch_20260309"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • use_cache: optional boolean

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  • BetaWebSearchTool20260318 object

    • type: "web_search_20260318"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • response_inclusion: optional "full" or "excluded"

      How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

      • "full"

      • "excluded"

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

  • BetaWebFetchTool20260318 object

    • type: "web_fetch_20260318"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • response_inclusion: optional "full" or "excluded"

      How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

      • "full"

      • "excluded"

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • use_cache: optional boolean

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  • BetaAdvisorTool20260301 object

    • type: "advisor_20260301"

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

    • name: "advisor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • caching: optional BetaCacheControlEphemeral or null

      Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_tokens: optional number or null

      Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

      minimum: 1024

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolSearchToolBm25_20251119 object

    • type: "tool_search_tool_bm25_20251119" or "tool_search_tool_bm25"

      • "tool_search_tool_bm25_20251119"

      • "tool_search_tool_bm25"

    • name: "tool_search_tool_bm25"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolSearchToolRegex20251119 object

    • type: "tool_search_tool_regex_20251119" or "tool_search_tool_regex"

      • "tool_search_tool_regex_20251119"

      • "tool_search_tool_regex"

    • name: "tool_search_tool_regex"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaMCPToolset object

    Configuration for a group of tools from an MCP server.

    Allows configuring enabled status and defer_loading for all tools from an MCP server, with optional per-tool overrides.

    • type: "mcp_toolset"

    • mcp_server_name: string

      Name of the MCP server to configure tools for

      maxLength: 255, minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional map[BetaMCPToolConfig] or null

      Configuration overrides for specific tools, keyed by tool name

      • defer_loading: optional boolean

      • enabled: optional boolean

    • default_config: optional BetaMCPToolDefaultConfig

      Default configuration applied to all tools from this server

      • defer_loading: optional boolean

      • enabled: optional boolean

• output_format: optional BetaJSONOutputFormat or null

  Deprecated

  Deprecated: Use output_config.format instead. See structured outputs

  A schema to specify Claude's output format in responses. This parameter will be removed in a future release.

Returns

• BetaMessageTokensCount object

  • context_management: BetaCountTokensContextManagementResponse or null

    Information about context management applied to the message.

    • original_input_tokens: number

      The original token count before context management was applied

  • input_tokens: number

    The total number of tokens across the provided list of messages, system prompt, and tools.

Example

curl https://api.anthropic.com/v1/messages/count_tokens \
    -H 'Content-Type: application/json' \
    -H 'anthropic-version: 2023-06-01' \
    -H "X-Api-Key: $ANTHROPIC_API_KEY" \
    -d '{
          "messages": [
            {
              "content": "Hello, world",
              "role": "user"
            }
          ],
          "model": "claude-opus-5",
          "system": [
            {
              "text": "Today'\''s date is 2024-06-01.",
              "type": "text"
            }
          ],
          "thinking": {
            "type": "adaptive"
          },
          "tools": [
            {
              "input_schema": {
                "type": "object",
                "properties": {
                  "location": "bar",
                  "unit": "bar"
                },
                "required": [
                  "location"
                ]
              },
              "name": "name"
            }
          ]
        }'

Response (200)

{
  "context_management": {
    "original_input_tokens": 0
  },
  "input_tokens": 2095
}

Domain types

Beta Advisor Message Iteration Usage

• BetaAdvisorMessageIterationUsage object

  Token usage for an advisor sub-inference iteration.

  • type: "advisor_message"

    Usage for an advisor sub-inference iteration

    default: advisor_message

  • cache_creation: BetaCacheCreation or null

    Breakdown of cached tokens by TTL

    • ephemeral_1h_input_tokens: number

      The number of input tokens used to create the 1 hour cache entry.

      default: 0, minimum: 0

    • ephemeral_5m_input_tokens: number

      The number of input tokens used to create the 5 minute cache entry.

      default: 0, minimum: 0

  • cache_creation_input_tokens: number

    The number of input tokens used to create the cache entry.

    default: 0, minimum: 0

  • cache_read_input_tokens: number

    The number of input tokens read from the cache.

    default: 0, minimum: 0

  • input_tokens: number

    The number of input tokens which were used.

    minimum: 0

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1"

        Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

      • "claude-mythos-5-1"

        Our most capable model for cybersecurity and biology research, available through trusted access programs

      • "claude-sonnet-5"

        High-performance model for coding and agents

      • "claude-fable-5"

        Next generation of intelligence for the hardest knowledge work and coding problems

      • "claude-mythos-5"

        Most capable model for cybersecurity and biology research

      • "claude-opus-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-8"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-7"

        Powerful intelligence for long-running agents and coding

      • "claude-mythos-preview"

        New class of intelligence, strongest in coding and cybersecurity

      • "claude-opus-4-6"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-6"

        Best combination of speed and intelligence

      • "claude-haiku-4-5"

        Fastest model with near-frontier intelligence

      • "claude-haiku-4-5-20251001"

        Fastest model with near-frontier intelligence

      • "claude-opus-4-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-5-20251101"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-5"

        High-performance model for agents and coding

      • "claude-sonnet-4-5-20250929"

        High-performance model for agents and coding

    • string

  • output_tokens: number

    The number of output tokens which were used.

    minimum: 0

Beta Advisor Redacted Result Block

• BetaAdvisorRedactedResultBlock object

  • type: "advisor_redacted_result"

    default: advisor_redacted_result

  • encrypted_content: string

    Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

  • stop_reason: string or null

    The advisor sub-inference's stop reason (same values as the top-level message stop_reason).

Beta Advisor Redacted Result Block Param

• BetaAdvisorRedactedResultBlockParam object

  • type: "advisor_redacted_result"

  • encrypted_content: string

    Opaque blob produced by a prior response; must be round-tripped verbatim.

  • stop_reason: optional string or null

Beta Advisor Result Block

• BetaAdvisorResultBlock object

  • type: "advisor_result"

    default: advisor_result

  • stop_reason: string or null

    The advisor sub-inference's stop reason (same values as the top-level message stop_reason). max_tokens indicates the advisor's output was truncated at the tool's max_tokens value or the advisor model's policy cap.

  • text: string

Beta Advisor Result Block Param

• BetaAdvisorResultBlockParam object

  • type: "advisor_result"

  • text: string

  • stop_reason: optional string or null

Beta Advisor Tool 20260301

• BetaAdvisorTool20260301 object

  • type: "advisor_20260301"

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1"

        Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

      • "claude-mythos-5-1"

        Our most capable model for cybersecurity and biology research, available through trusted access programs

      • "claude-sonnet-5"

        High-performance model for coding and agents

      • "claude-fable-5"

        Next generation of intelligence for the hardest knowledge work and coding problems

      • "claude-mythos-5"

        Most capable model for cybersecurity and biology research

      • "claude-opus-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-8"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-7"

        Powerful intelligence for long-running agents and coding

      • "claude-mythos-preview"

        New class of intelligence, strongest in coding and cybersecurity

      • "claude-opus-4-6"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-6"

        Best combination of speed and intelligence

      • "claude-haiku-4-5"

        Fastest model with near-frontier intelligence

      • "claude-haiku-4-5-20251001"

        Fastest model with near-frontier intelligence

      • "claude-opus-4-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-5-20251101"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-5"

        High-performance model for agents and coding

      • "claude-sonnet-4-5-20250929"

        High-performance model for agents and coding

    • string

  • name: "advisor"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • caching: optional BetaCacheControlEphemeral or null

    Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • max_tokens: optional number or null

    Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

    minimum: 1024

  • max_uses: optional number or null

    Maximum number of times the tool can be used in the API request.

    exclusiveMinimum: 0

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Advisor Tool Result Block

• BetaAdvisorToolResultBlock object

  • type: "advisor_tool_result"

    default: advisor_tool_result

  • content: BetaAdvisorToolResultError or BetaAdvisorResultBlock or BetaAdvisorRedactedResultBlock

    • BetaAdvisorToolResultError object

      • type: "advisor_tool_result_error"

        default: advisor_tool_result_error

      • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

        • "max_uses_exceeded"

        • "prompt_too_long"

        • "too_many_requests"

        • "overloaded"

        • "unavailable"

        • "execution_time_exceeded"

        • "model_not_found"

    • BetaAdvisorResultBlock object

      • type: "advisor_result"

        default: advisor_result

      • stop_reason: string or null

        The advisor sub-inference's stop reason (same values as the top-level message stop_reason). max_tokens indicates the advisor's output was truncated at the tool's max_tokens value or the advisor model's policy cap.

      • text: string

    • BetaAdvisorRedactedResultBlock object

      • type: "advisor_redacted_result"

        default: advisor_redacted_result

      • encrypted_content: string

        Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

      • stop_reason: string or null

        The advisor sub-inference's stop reason (same values as the top-level message stop_reason).

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Advisor Tool Result Block Param

• BetaAdvisorToolResultBlockParam object

  • type: "advisor_tool_result"

  • content: BetaAdvisorToolResultErrorParam or BetaAdvisorResultBlockParam or BetaAdvisorRedactedResultBlockParam

    • BetaAdvisorToolResultErrorParam object

      • type: "advisor_tool_result_error"

      • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

        • "max_uses_exceeded"

        • "prompt_too_long"

        • "too_many_requests"

        • "overloaded"

        • "unavailable"

        • "execution_time_exceeded"

        • "model_not_found"

    • BetaAdvisorResultBlockParam object

      • type: "advisor_result"

      • text: string

      • stop_reason: optional string or null

    • BetaAdvisorRedactedResultBlockParam object

      • type: "advisor_redacted_result"

      • encrypted_content: string

        Opaque blob produced by a prior response; must be round-tripped verbatim.

      • stop_reason: optional string or null

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta Advisor Tool Result Error

• BetaAdvisorToolResultError object

  • type: "advisor_tool_result_error"

    default: advisor_tool_result_error

  • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

    • "max_uses_exceeded"

    • "prompt_too_long"

    • "too_many_requests"

    • "overloaded"

    • "unavailable"

    • "execution_time_exceeded"

    • "model_not_found"

Beta Advisor Tool Result Error Param

• BetaAdvisorToolResultErrorParam object

  • type: "advisor_tool_result_error"

  • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

    • "max_uses_exceeded"

    • "prompt_too_long"

    • "too_many_requests"

    • "overloaded"

    • "unavailable"

    • "execution_time_exceeded"

    • "model_not_found"

Beta All Thinking Turns

• BetaAllThinkingTurns object

  • type: "all"

Beta Base64 Image Source

• BetaBase64ImageSource object

  • type: "base64"

  • data: string

    format: byte

  • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

    • "image/jpeg"

    • "image/png"

    • "image/gif"

    • "image/webp"

Beta Base64 PDF Source

• BetaBase64PDFSource object

  • type: "base64"

  • data: string

    format: byte

  • media_type: "application/pdf"

Beta Bash Code Execution Output Block

• BetaBashCodeExecutionOutputBlock object

  • type: "bash_code_execution_output"

    default: bash_code_execution_output

  • file_id: string

Beta Bash Code Execution Output Block Param

• BetaBashCodeExecutionOutputBlockParam object

  • type: "bash_code_execution_output"

  • file_id: string

Beta Bash Code Execution Result Block

• BetaBashCodeExecutionResultBlock object

  • type: "bash_code_execution_result"

    default: bash_code_execution_result

  • content: array of BetaBashCodeExecutionOutputBlock

    • type: "bash_code_execution_output"

      default: bash_code_execution_output

    • file_id: string

  • return_code: number

  • stderr: string

  • stdout: string

Beta Bash Code Execution Result Block Param

• BetaBashCodeExecutionResultBlockParam object

  • type: "bash_code_execution_result"

  • content: array of BetaBashCodeExecutionOutputBlockParam

    • type: "bash_code_execution_output"

    • file_id: string

  • return_code: number

  • stderr: string

  • stdout: string

Beta Bash Code Execution Tool Result Block

• BetaBashCodeExecutionToolResultBlock object

  • type: "bash_code_execution_tool_result"

    default: bash_code_execution_tool_result

  • content: BetaBashCodeExecutionToolResultError or BetaBashCodeExecutionResultBlock

    • BetaBashCodeExecutionToolResultError object

      • type: "bash_code_execution_tool_result_error"

        default: bash_code_execution_tool_result_error

      • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

        • "invalid_tool_input"

        • "unavailable"

        • "too_many_requests"

        • "execution_time_exceeded"

        • "output_file_too_large"

    • BetaBashCodeExecutionResultBlock object

      • type: "bash_code_execution_result"

        default: bash_code_execution_result

      • content: array of BetaBashCodeExecutionOutputBlock

        • type: "bash_code_execution_output"

          default: bash_code_execution_output

        • file_id: string

      • return_code: number

      • stderr: string

      • stdout: string

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Bash Code Execution Tool Result Block Param

• BetaBashCodeExecutionToolResultBlockParam object

  • type: "bash_code_execution_tool_result"

  • content: BetaBashCodeExecutionToolResultErrorParam or BetaBashCodeExecutionResultBlockParam

    • BetaBashCodeExecutionToolResultErrorParam object

      • type: "bash_code_execution_tool_result_error"

      • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

        • "invalid_tool_input"

        • "unavailable"

        • "too_many_requests"

        • "execution_time_exceeded"

        • "output_file_too_large"

    • BetaBashCodeExecutionResultBlockParam object

      • type: "bash_code_execution_result"

      • content: array of BetaBashCodeExecutionOutputBlockParam

        • type: "bash_code_execution_output"

        • file_id: string

      • return_code: number

      • stderr: string

      • stdout: string

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta Bash Code Execution Tool Result Error

• BetaBashCodeExecutionToolResultError object

  • type: "bash_code_execution_tool_result_error"

    default: bash_code_execution_tool_result_error

  • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

    • "invalid_tool_input"

    • "unavailable"

    • "too_many_requests"

    • "execution_time_exceeded"

    • "output_file_too_large"

Beta Bash Code Execution Tool Result Error Param

• BetaBashCodeExecutionToolResultErrorParam object

  • type: "bash_code_execution_tool_result_error"

  • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

    • "invalid_tool_input"

    • "unavailable"

    • "too_many_requests"

    • "execution_time_exceeded"

    • "output_file_too_large"

Beta Browser Close Tab Config

• BetaBrowserCloseTabConfig object

  close_tab's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Double Click Config

• BetaBrowserDoubleClickConfig object

  double_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser File Upload Config

• BetaBrowserFileUploadConfig object

  file_upload's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Find Config

• BetaBrowserFindConfig object

  find's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Form Input Config

• BetaBrowserFormInputConfig object

  form_input's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Get Page Text Config

• BetaBrowserGetPageTextConfig object

  get_page_text's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Hold Key Config

• BetaBrowserHoldKeyConfig object

  hold_key's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Hover Config

• BetaBrowserHoverConfig object

  hover's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Javascript Exec Config

• BetaBrowserJavascriptExecConfig object

  javascript_exec's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Key Config

• BetaBrowserKeyConfig object

  key's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Left Click Config

• BetaBrowserLeftClickConfig object

  left_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Left Click Drag Config

• BetaBrowserLeftClickDragConfig object

  left_click_drag's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Left Mouse Down Config

• BetaBrowserLeftMouseDownConfig object

  left_mouse_down's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Left Mouse Up Config

• BetaBrowserLeftMouseUpConfig object

  left_mouse_up's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser List Tabs Config

• BetaBrowserListTabsConfig object

  list_tabs's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Middle Click Config

• BetaBrowserMiddleClickConfig object

  middle_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Mouse Move Config

• BetaBrowserMouseMoveConfig object

  mouse_move's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Navigate Config

• BetaBrowserNavigateConfig object

  navigate's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser New Tab Config

• BetaBrowserNewTabConfig object

  new_tab's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Read Console Config

• BetaBrowserReadConsoleConfig object

  read_console's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Read Network Config

• BetaBrowserReadNetworkConfig object

  read_network's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Read Page Config

• BetaBrowserReadPageConfig object

  read_page's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Right Click Config

• BetaBrowserRightClickConfig object

  right_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Screenshot Config

• BetaBrowserScreenshotConfig object

  screenshot's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Scroll Config

• BetaBrowserScrollConfig object

  scroll's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Scroll To Config

• BetaBrowserScrollToConfig object

  scroll_to's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser State Block Param

• BetaBrowserStateBlockParam object

  The caller's browser state after a browser toolset member call — the full inventory of open tabs, which tab is active, and any side effects (tabs opened, download state changes) the call produced.

  At most one per tool_result, only on a non-error result answering a browser toolset member tool_use. The server renders the model-visible text from it; the model never sees the raw fields.

  • type: "browser_state"

  • tabs: array of BetaBrowserStateTabEntry

    All tabs open in the browser after this call — the full inventory, not a delta. May be empty. Whenever non-empty, exactly one entry carries active: true.

    maxItems: 100

    • tab_id: string

      The caller-assigned identifier for this tab, unique within the inventory.

      maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • title: string

      The title of the page the tab is showing. May be empty.

      maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • url: string

      The URL of the page the tab is showing. May be empty.

      maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • active: optional boolean

      Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • state_changes: optional array of BetaBrowserStateChange or null

    Tabs opened and download state changes during this call. "Nothing to report" is expressed by omitting the field, never by an empty list.

    maxItems: 200, minItems: 1

    • BetaBrowserStateChangeTabOpened object

      A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

      Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

      • type: "tab_opened"

      • tab_id: string

        The tab_id of the opened tab, present in tabs.

        maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • BetaBrowserStateChangeDownloadStarted object

      A file download that started during this call.

      • type: "download_started"

      • download_id: string

        The caller-assigned identifier for this download, stable across the state changes reporting it.

        maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

      • url: string

        The final post-redirect URL the download was served from.

        maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • BetaBrowserStateChangeDownloadCompleted object

      A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

      • type: "download_completed"

      • download_id: string

        The caller-assigned identifier for this download, stable across the state changes reporting it.

        maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

      • url: string

        The final post-redirect URL the download was served from.

        maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

      • path: optional string or null

        Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

        pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

      • size_bytes: optional number or null

        The completed download's size.

        minimum: 0

    • BetaBrowserStateChangeDownloadFailed object

      A file download that failed — or was cancelled — during this call.

      • type: "download_failed"

      • download_id: string

        The caller-assigned identifier for this download, stable across the state changes reporting it.

        maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

      • url: string

        The final post-redirect URL the download was served from.

        maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

      • error: optional string or null

        The failure or cancellation detail, when known.

        pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

Beta Browser State Change

• BetaBrowserStateChange = BetaBrowserStateChangeTabOpened or BetaBrowserStateChangeDownloadStarted or BetaBrowserStateChangeDownloadCompleted or BetaBrowserStateChangeDownloadFailed

  A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

  Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

  • BetaBrowserStateChangeTabOpened object

    A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

    Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

    • type: "tab_opened"

    • tab_id: string

      The tab_id of the opened tab, present in tabs.

      maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • BetaBrowserStateChangeDownloadStarted object

    A file download that started during this call.

    • type: "download_started"

    • download_id: string

      The caller-assigned identifier for this download, stable across the state changes reporting it.

      maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • url: string

      The final post-redirect URL the download was served from.

      maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • BetaBrowserStateChangeDownloadCompleted object

    A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

    • type: "download_completed"

    • download_id: string

      The caller-assigned identifier for this download, stable across the state changes reporting it.

      maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • url: string

      The final post-redirect URL the download was served from.

      maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • path: optional string or null

      Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

      pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

    • size_bytes: optional number or null

      The completed download's size.

      minimum: 0

  • BetaBrowserStateChangeDownloadFailed object

    A file download that failed — or was cancelled — during this call.

    • type: "download_failed"

    • download_id: string

      The caller-assigned identifier for this download, stable across the state changes reporting it.

      maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • url: string

      The final post-redirect URL the download was served from.

      maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

    • error: optional string or null

      The failure or cancellation detail, when known.

      pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

Beta Browser State Change Download Completed

• BetaBrowserStateChangeDownloadCompleted object

  A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

  • type: "download_completed"

  • download_id: string

    The caller-assigned identifier for this download, stable across the state changes reporting it.

    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • url: string

    The final post-redirect URL the download was served from.

    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • path: optional string or null

    Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

    pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

  • size_bytes: optional number or null

    The completed download's size.

    minimum: 0

Beta Browser State Change Download Failed

• BetaBrowserStateChangeDownloadFailed object

  A file download that failed — or was cancelled — during this call.

  • type: "download_failed"

  • download_id: string

    The caller-assigned identifier for this download, stable across the state changes reporting it.

    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • url: string

    The final post-redirect URL the download was served from.

    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • error: optional string or null

    The failure or cancellation detail, when known.

    pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

Beta Browser State Change Download Started

• BetaBrowserStateChangeDownloadStarted object

  A file download that started during this call.

  • type: "download_started"

  • download_id: string

    The caller-assigned identifier for this download, stable across the state changes reporting it.

    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • url: string

    The final post-redirect URL the download was served from.

    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

Beta Browser State Change Tab Opened

• BetaBrowserStateChangeTabOpened object

  A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

  Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

  • type: "tab_opened"

  • tab_id: string

    The tab_id of the opened tab, present in tabs.

    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

Beta Browser State Tab Entry

• BetaBrowserStateTabEntry object

  One open browser tab reported in a browser_state block's tabs inventory.

  tab_id is the caller-assigned identifier for the tab; title and url describe the page the tab is currently showing and may be empty strings (a blank tab legitimately has both empty). active marks the tab that is active after this call; whenever tabs is non-empty, exactly one entry is marked.

  • tab_id: string

    The caller-assigned identifier for this tab, unique within the inventory.

    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • title: string

    The title of the page the tab is showing. May be empty.

    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • url: string

    The URL of the page the tab is showing. May be empty.

    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

  • active: optional boolean

    Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

Beta Browser Switch Tab Config

• BetaBrowserSwitchTabConfig object

  switch_tab's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Toolset 20260801

• BetaBrowserToolset20260801 object

  The browser toolset: a single tools[] entry (carrying no name) that declares the browser tool family. The model is served the family's tool with any members disabled via configs removed from its schema.

  • type: "browser_toolset_20260801"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • configs: optional BetaBrowserToolsetConfigs or null

    Per-member configuration for browser_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

    • type: optional BetaBrowserTypeConfig or null

      type's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • close_tab: optional BetaBrowserCloseTabConfig or null

      close_tab's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • double_click: optional BetaBrowserDoubleClickConfig or null

      double_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • file_upload: optional BetaBrowserFileUploadConfig or null

      file_upload's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • find: optional BetaBrowserFindConfig or null

      find's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • form_input: optional BetaBrowserFormInputConfig or null

      form_input's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • get_page_text: optional BetaBrowserGetPageTextConfig or null

      get_page_text's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • hold_key: optional BetaBrowserHoldKeyConfig or null

      hold_key's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • hover: optional BetaBrowserHoverConfig or null

      hover's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • javascript_exec: optional BetaBrowserJavascriptExecConfig or null

      javascript_exec's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • key: optional BetaBrowserKeyConfig or null

      key's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • left_click: optional BetaBrowserLeftClickConfig or null

      left_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • left_click_drag: optional BetaBrowserLeftClickDragConfig or null

      left_click_drag's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • left_mouse_down: optional BetaBrowserLeftMouseDownConfig or null

      left_mouse_down's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • left_mouse_up: optional BetaBrowserLeftMouseUpConfig or null

      left_mouse_up's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • list_tabs: optional BetaBrowserListTabsConfig or null

      list_tabs's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • middle_click: optional BetaBrowserMiddleClickConfig or null

      middle_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • mouse_move: optional BetaBrowserMouseMoveConfig or null

      mouse_move's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • navigate: optional BetaBrowserNavigateConfig or null

      navigate's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • new_tab: optional BetaBrowserNewTabConfig or null

      new_tab's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • read_console: optional BetaBrowserReadConsoleConfig or null

      read_console's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • read_network: optional BetaBrowserReadNetworkConfig or null

      read_network's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • read_page: optional BetaBrowserReadPageConfig or null

      read_page's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • right_click: optional BetaBrowserRightClickConfig or null

      right_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • screenshot: optional BetaBrowserScreenshotConfig or null

      screenshot's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • scroll: optional BetaBrowserScrollConfig or null

      scroll's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • scroll_to: optional BetaBrowserScrollToConfig or null

      scroll_to's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • switch_tab: optional BetaBrowserSwitchTabConfig or null

      switch_tab's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • triple_click: optional BetaBrowserTripleClickConfig or null

      triple_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • wait: optional BetaBrowserWaitConfig or null

      wait's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • zoom: optional BetaBrowserZoomConfig or null

      zoom's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Toolset Configs

• BetaBrowserToolsetConfigs object

  Per-member configuration for browser_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

  • type: optional BetaBrowserTypeConfig or null

    type's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • close_tab: optional BetaBrowserCloseTabConfig or null

    close_tab's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • double_click: optional BetaBrowserDoubleClickConfig or null

    double_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • file_upload: optional BetaBrowserFileUploadConfig or null

    file_upload's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • find: optional BetaBrowserFindConfig or null

    find's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • form_input: optional BetaBrowserFormInputConfig or null

    form_input's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • get_page_text: optional BetaBrowserGetPageTextConfig or null

    get_page_text's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • hold_key: optional BetaBrowserHoldKeyConfig or null

    hold_key's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • hover: optional BetaBrowserHoverConfig or null

    hover's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • javascript_exec: optional BetaBrowserJavascriptExecConfig or null

    javascript_exec's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • key: optional BetaBrowserKeyConfig or null

    key's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • left_click: optional BetaBrowserLeftClickConfig or null

    left_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • left_click_drag: optional BetaBrowserLeftClickDragConfig or null

    left_click_drag's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • left_mouse_down: optional BetaBrowserLeftMouseDownConfig or null

    left_mouse_down's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • left_mouse_up: optional BetaBrowserLeftMouseUpConfig or null

    left_mouse_up's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • list_tabs: optional BetaBrowserListTabsConfig or null

    list_tabs's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • middle_click: optional BetaBrowserMiddleClickConfig or null

    middle_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • mouse_move: optional BetaBrowserMouseMoveConfig or null

    mouse_move's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • navigate: optional BetaBrowserNavigateConfig or null

    navigate's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • new_tab: optional BetaBrowserNewTabConfig or null

    new_tab's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • read_console: optional BetaBrowserReadConsoleConfig or null

    read_console's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • read_network: optional BetaBrowserReadNetworkConfig or null

    read_network's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • read_page: optional BetaBrowserReadPageConfig or null

    read_page's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • right_click: optional BetaBrowserRightClickConfig or null

    right_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • screenshot: optional BetaBrowserScreenshotConfig or null

    screenshot's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • scroll: optional BetaBrowserScrollConfig or null

    scroll's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • scroll_to: optional BetaBrowserScrollToConfig or null

    scroll_to's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • switch_tab: optional BetaBrowserSwitchTabConfig or null

    switch_tab's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • triple_click: optional BetaBrowserTripleClickConfig or null

    triple_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • wait: optional BetaBrowserWaitConfig or null

    wait's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • zoom: optional BetaBrowserZoomConfig or null

    zoom's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Triple Click Config

• BetaBrowserTripleClickConfig object

  triple_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Type Config

• BetaBrowserTypeConfig object

  type's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Wait Config

• BetaBrowserWaitConfig object

  wait's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Browser Zoom Config

• BetaBrowserZoomConfig object

  zoom's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Cache Control Ephemeral

• BetaCacheControlEphemeral object

  • type: "ephemeral"

  • ttl: optional "5m" or "1h"

    The time-to-live for the cache control breakpoint.

    This may be one the following values:

    • 5m: 5 minutes
    • 1h: 1 hour

    Defaults to 5m. See prompt caching pricing for details.

    • "5m"

    • "1h"

Beta Cache Creation

• BetaCacheCreation object

  • ephemeral_1h_input_tokens: number

    The number of input tokens used to create the 1 hour cache entry.

    default: 0, minimum: 0

  • ephemeral_5m_input_tokens: number

    The number of input tokens used to create the 5 minute cache entry.

    default: 0, minimum: 0

Beta Cache Miss Messages Changed

• BetaCacheMissMessagesChanged object

  • type: "messages_changed"

    default: messages_changed

  • cache_missed_input_tokens: number

    Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

Beta Cache Miss Model Changed

• BetaCacheMissModelChanged object

  • type: "model_changed"

    default: model_changed

  • cache_missed_input_tokens: number

    Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

Beta Cache Miss Previous Message Not Found

• BetaCacheMissPreviousMessageNotFound object

  • type: "previous_message_not_found"

    default: previous_message_not_found

Beta Cache Miss System Changed

• BetaCacheMissSystemChanged object

  • type: "system_changed"

    default: system_changed

  • cache_missed_input_tokens: number

    Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

Beta Cache Miss Tools Changed

• BetaCacheMissToolsChanged object

  • type: "tools_changed"

    default: tools_changed

  • cache_missed_input_tokens: number

    Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

Beta Cache Miss Unavailable

• BetaCacheMissUnavailable object

  • type: "unavailable"

    default: unavailable

Beta Citation Char Location

• BetaCitationCharLocation object

  • type: "char_location"

    default: char_location

  • cited_text: string

  • document_index: number

    minimum: 0

  • document_title: string or null

  • end_char_index: number

  • file_id: string or null

  • start_char_index: number

    minimum: 0

Beta Citation Char Location Param

• BetaCitationCharLocationParam object

  • type: "char_location"

  • cited_text: string

  • document_index: number

    minimum: 0

  • document_title: string or null

    maxLength: 500, minLength: 1

  • end_char_index: number

  • start_char_index: number

    minimum: 0

Beta Citation Config

• BetaCitationConfig object

  • enabled: boolean

    default: false

Beta Citation Content Block Location

• BetaCitationContentBlockLocation object

  • type: "content_block_location"

    default: content_block_location

  • cited_text: string

    The full text of the cited block range, concatenated.

    Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

  • document_index: number

    minimum: 0

  • document_title: string or null

  • end_block_index: number

    Exclusive 0-based end index of the cited block range in the source's content array.

    Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

  • file_id: string or null

  • start_block_index: number

    0-based index of the first cited block in the source's content array.

    minimum: 0

Beta Citation Content Block Location Param

• BetaCitationContentBlockLocationParam object

  • type: "content_block_location"

  • cited_text: string

    The full text of the cited block range, concatenated.

    Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

  • document_index: number

    minimum: 0

  • document_title: string or null

    maxLength: 500, minLength: 1

  • end_block_index: number

    Exclusive 0-based end index of the cited block range in the source's content array.

    Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

  • start_block_index: number

    0-based index of the first cited block in the source's content array.

    minimum: 0

Beta Citation Page Location

• BetaCitationPageLocation object

  • type: "page_location"

    default: page_location

  • cited_text: string

  • document_index: number

    minimum: 0

  • document_title: string or null

  • end_page_number: number

  • file_id: string or null

  • start_page_number: number

    minimum: 1

Beta Citation Page Location Param

• BetaCitationPageLocationParam object

  • type: "page_location"

  • cited_text: string

  • document_index: number

    minimum: 0

  • document_title: string or null

    maxLength: 500, minLength: 1

  • end_page_number: number

  • start_page_number: number

    minimum: 1

Beta Citation Search Result Location

• BetaCitationSearchResultLocation object

  • type: "search_result_location"

    default: search_result_location

  • cited_text: string

    The full text of the cited block range, concatenated.

    Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

  • end_block_index: number

    Exclusive 0-based end index of the cited block range in the source's content array.

    Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

  • search_result_index: number

    0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

    Counted separately from document_index; server-side web search results are not included in this count.

    minimum: 0

  • source: string

  • start_block_index: number

    0-based index of the first cited block in the source's content array.

    minimum: 0

  • title: string or null

Beta Citation Search Result Location Param

• BetaCitationSearchResultLocationParam object

  • type: "search_result_location"

  • cited_text: string

    The full text of the cited block range, concatenated.

    Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

  • end_block_index: number

    Exclusive 0-based end index of the cited block range in the source's content array.

    Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

  • search_result_index: number

    0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

    Counted separately from document_index; server-side web search results are not included in this count.

    minimum: 0

  • source: string

  • start_block_index: number

    0-based index of the first cited block in the source's content array.

    minimum: 0

  • title: string or null

Beta Citation Web Search Result Location Param

• BetaCitationWebSearchResultLocationParam object

  • type: "web_search_result_location"

  • cited_text: string

  • encrypted_index: string

  • title: string or null

    maxLength: 512, minLength: 1

  • url: string

    minLength: 1

Beta Citations Config Param

• BetaCitationsConfigParam object

  • enabled: optional boolean

Beta Citations Delta

• BetaCitationsDelta object

  • type: "citations_delta"

    default: citations_delta

  • citation: BetaCitationCharLocation or BetaCitationPageLocation or BetaCitationContentBlockLocation or 2 more

    • BetaCitationCharLocation object

      • type: "char_location"

        default: char_location

      • cited_text: string

      • document_index: number

        minimum: 0

      • document_title: string or null

      • end_char_index: number

      • file_id: string or null

      • start_char_index: number

        minimum: 0

    • BetaCitationPageLocation object

      • type: "page_location"

        default: page_location

      • cited_text: string

      • document_index: number

        minimum: 0

      • document_title: string or null

      • end_page_number: number

      • file_id: string or null

      • start_page_number: number

        minimum: 1

    • BetaCitationContentBlockLocation object

      • type: "content_block_location"

        default: content_block_location

      • cited_text: string

        The full text of the cited block range, concatenated.

        Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      • document_index: number

        minimum: 0

      • document_title: string or null

      • end_block_index: number

        Exclusive 0-based end index of the cited block range in the source's content array.

        Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

      • file_id: string or null

      • start_block_index: number

        0-based index of the first cited block in the source's content array.

        minimum: 0

    • BetaCitationsWebSearchResultLocation object

      • type: "web_search_result_location"

        default: web_search_result_location

      • cited_text: string

      • encrypted_index: string

      • title: string or null

        maxLength: 512

      • url: string

    • BetaCitationSearchResultLocation object

      • type: "search_result_location"

        default: search_result_location

      • cited_text: string

        The full text of the cited block range, concatenated.

        Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      • end_block_index: number

        Exclusive 0-based end index of the cited block range in the source's content array.

        Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

      • search_result_index: number

        0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

        Counted separately from document_index; server-side web search results are not included in this count.

        minimum: 0

      • source: string

      • start_block_index: number

        0-based index of the first cited block in the source's content array.

        minimum: 0

      • title: string or null

Beta Citations Web Search Result Location

• BetaCitationsWebSearchResultLocation object

  • type: "web_search_result_location"

    default: web_search_result_location

  • cited_text: string

  • encrypted_index: string

  • title: string or null

    maxLength: 512

  • url: string

Beta Clear Thinking 20251015 Edit

• BetaClearThinking20251015Edit object

  • type: "clear_thinking_20251015"

  • keep: optional BetaThinkingTurns or BetaAllThinkingTurns or "all"

    Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

    • BetaThinkingTurns object

      • type: "thinking_turns"

      • value: number

        minimum: 1

    • BetaAllThinkingTurns object

      • type: "all"

    • "all"

Beta Clear Thinking 20251015 Edit Response

• BetaClearThinking20251015EditResponse object

  • type: "clear_thinking_20251015"

    The type of context management edit applied.

    default: clear_thinking_20251015

  • cleared_input_tokens: number

    Number of input tokens cleared by this edit.

    minimum: 0

  • cleared_thinking_turns: number

    Number of thinking turns that were cleared.

    minimum: 0

Beta Clear Tool Uses 20250919 Edit

• BetaClearToolUses20250919Edit object

  • type: "clear_tool_uses_20250919"

  • clear_at_least: optional BetaInputTokensClearAtLeast or null

    Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

    • type: "input_tokens"

    • value: number

      minimum: 0

  • clear_tool_inputs: optional boolean or array of string or null

    Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

    • boolean

    • array of string

  • exclude_tools: optional array of string or null

    Tool names whose uses are preserved from clearing

  • keep: optional BetaToolUsesKeep

    Number of tool uses to retain in the conversation

    • type: "tool_uses"

    • value: number

      minimum: 0

  • trigger: optional BetaInputTokensTrigger or BetaToolUsesTrigger

    Condition that triggers the context management strategy

    • BetaInputTokensTrigger object

      • type: "input_tokens"

      • value: number

        minimum: 1

    • BetaToolUsesTrigger object

      • type: "tool_uses"

      • value: number

        minimum: 1

Beta Clear Tool Uses 20250919 Edit Response

• BetaClearToolUses20250919EditResponse object

  • type: "clear_tool_uses_20250919"

    The type of context management edit applied.

    default: clear_tool_uses_20250919

  • cleared_input_tokens: number

    Number of input tokens cleared by this edit.

    minimum: 0

  • cleared_tool_uses: number

    Number of tool uses that were cleared.

    minimum: 0

Beta Code Execution Output Block

• BetaCodeExecutionOutputBlock object

  • type: "code_execution_output"

    default: code_execution_output

  • file_id: string

Beta Code Execution Output Block Param

• BetaCodeExecutionOutputBlockParam object

  • type: "code_execution_output"

  • file_id: string

Beta Code Execution Result Block

• BetaCodeExecutionResultBlock object

  • type: "code_execution_result"

    default: code_execution_result

  • content: array of BetaCodeExecutionOutputBlock

    • type: "code_execution_output"

      default: code_execution_output

    • file_id: string

  • return_code: number

  • stderr: string

  • stdout: string

Beta Code Execution Result Block Param

• BetaCodeExecutionResultBlockParam object

  • type: "code_execution_result"

  • content: array of BetaCodeExecutionOutputBlockParam

    • type: "code_execution_output"

    • file_id: string

  • return_code: number

  • stderr: string

  • stdout: string

Beta Code Execution Tool 20250522

• BetaCodeExecutionTool20250522 object

  • type: "code_execution_20250522"

  • name: "code_execution"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Code Execution Tool 20250825

• BetaCodeExecutionTool20250825 object

  • type: "code_execution_20250825"

  • name: "code_execution"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Code Execution Tool 20260120

• BetaCodeExecutionTool20260120 object

  Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

  • type: "code_execution_20260120"

  • name: "code_execution"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Code Execution Tool 20260521

• BetaCodeExecutionTool20260521 object

  Code execution tool with REPL state persistence.

  • type: "code_execution_20260521"

  • name: "code_execution"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Code Execution Tool Result Block

• BetaCodeExecutionToolResultBlock object

  • type: "code_execution_tool_result"

    default: code_execution_tool_result

  • content: BetaCodeExecutionToolResultBlockContent

    Code execution result with encrypted stdout for PFC + web_search results.

    • BetaCodeExecutionToolResultError object

      • type: "code_execution_tool_result_error"

        default: code_execution_tool_result_error

      • error_code: BetaCodeExecutionToolResultErrorCode

        • "invalid_tool_input"

        • "unavailable"

        • "too_many_requests"

        • "execution_time_exceeded"

    • BetaCodeExecutionResultBlock object

      • type: "code_execution_result"

        default: code_execution_result

      • content: array of BetaCodeExecutionOutputBlock

        • type: "code_execution_output"

          default: code_execution_output

        • file_id: string

      • return_code: number

      • stderr: string

      • stdout: string

    • BetaEncryptedCodeExecutionResultBlock object

      Code execution result with encrypted stdout for PFC + web_search results.

      • type: "encrypted_code_execution_result"

        default: encrypted_code_execution_result

      • content: array of BetaCodeExecutionOutputBlock

        • type: "code_execution_output"

          default: code_execution_output

        • file_id: string

      • encrypted_stdout: string

      • return_code: number

      • stderr: string

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Code Execution Tool Result Block Content

• BetaCodeExecutionToolResultBlockContent = BetaCodeExecutionToolResultError or BetaCodeExecutionResultBlock or BetaEncryptedCodeExecutionResultBlock

  Code execution result with encrypted stdout for PFC + web_search results.

  • BetaCodeExecutionToolResultError object

    • type: "code_execution_tool_result_error"

      default: code_execution_tool_result_error

    • error_code: BetaCodeExecutionToolResultErrorCode

      • "invalid_tool_input"

      • "unavailable"

      • "too_many_requests"

      • "execution_time_exceeded"

  • BetaCodeExecutionResultBlock object

    • type: "code_execution_result"

      default: code_execution_result

    • content: array of BetaCodeExecutionOutputBlock

      • type: "code_execution_output"

        default: code_execution_output

      • file_id: string

    • return_code: number

    • stderr: string

    • stdout: string

  • BetaEncryptedCodeExecutionResultBlock object

    Code execution result with encrypted stdout for PFC + web_search results.

    • type: "encrypted_code_execution_result"

      default: encrypted_code_execution_result

    • content: array of BetaCodeExecutionOutputBlock

      • type: "code_execution_output"

        default: code_execution_output

      • file_id: string

    • encrypted_stdout: string

    • return_code: number

    • stderr: string

Beta Code Execution Tool Result Block Param

• BetaCodeExecutionToolResultBlockParam object

  • type: "code_execution_tool_result"

  • content: BetaCodeExecutionToolResultBlockParamContent

    Code execution result with encrypted stdout for PFC + web_search results.

    • BetaCodeExecutionToolResultErrorParam object

      • type: "code_execution_tool_result_error"

      • error_code: BetaCodeExecutionToolResultErrorCode

        • "invalid_tool_input"

        • "unavailable"

        • "too_many_requests"

        • "execution_time_exceeded"

    • BetaCodeExecutionResultBlockParam object

      • type: "code_execution_result"

      • content: array of BetaCodeExecutionOutputBlockParam

        • type: "code_execution_output"

        • file_id: string

      • return_code: number

      • stderr: string

      • stdout: string

    • BetaEncryptedCodeExecutionResultBlockParam object

      Code execution result with encrypted stdout for PFC + web_search results.

      • type: "encrypted_code_execution_result"

      • content: array of BetaCodeExecutionOutputBlockParam

        • type: "code_execution_output"

        • file_id: string

      • encrypted_stdout: string

      • return_code: number

      • stderr: string

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta Code Execution Tool Result Block Param Content

• BetaCodeExecutionToolResultBlockParamContent = BetaCodeExecutionToolResultErrorParam or BetaCodeExecutionResultBlockParam or BetaEncryptedCodeExecutionResultBlockParam

  Code execution result with encrypted stdout for PFC + web_search results.

  • BetaCodeExecutionToolResultErrorParam object

    • type: "code_execution_tool_result_error"

    • error_code: BetaCodeExecutionToolResultErrorCode

      • "invalid_tool_input"

      • "unavailable"

      • "too_many_requests"

      • "execution_time_exceeded"

  • BetaCodeExecutionResultBlockParam object

    • type: "code_execution_result"

    • content: array of BetaCodeExecutionOutputBlockParam

      • type: "code_execution_output"

      • file_id: string

    • return_code: number

    • stderr: string

    • stdout: string

  • BetaEncryptedCodeExecutionResultBlockParam object

    Code execution result with encrypted stdout for PFC + web_search results.

    • type: "encrypted_code_execution_result"

    • content: array of BetaCodeExecutionOutputBlockParam

      • type: "code_execution_output"

      • file_id: string

    • encrypted_stdout: string

    • return_code: number

    • stderr: string

Beta Code Execution Tool Result Error

• BetaCodeExecutionToolResultError object

  • type: "code_execution_tool_result_error"

    default: code_execution_tool_result_error

  • error_code: BetaCodeExecutionToolResultErrorCode

    • "invalid_tool_input"

    • "unavailable"

    • "too_many_requests"

    • "execution_time_exceeded"

Beta Code Execution Tool Result Error Code

• BetaCodeExecutionToolResultErrorCode = "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

  • "invalid_tool_input"

  • "unavailable"

  • "too_many_requests"

  • "execution_time_exceeded"

Beta Code Execution Tool Result Error Param

• BetaCodeExecutionToolResultErrorParam object

  • type: "code_execution_tool_result_error"

  • error_code: BetaCodeExecutionToolResultErrorCode

    • "invalid_tool_input"

    • "unavailable"

    • "too_many_requests"

    • "execution_time_exceeded"

Beta Compact 20260112 Edit

• BetaCompact20260112Edit object

  Automatically compact older context when reaching the configured trigger threshold.

  • type: "compact_20260112"

  • instructions: optional string or null

    Additional instructions for summarization.

  • pause_after_compaction: optional boolean

    Whether to pause after compaction and return the compaction block to the user.

  • trigger: optional BetaInputTokensTrigger or null

    When to trigger compaction. Defaults to 150000 input tokens.

    • type: "input_tokens"

    • value: number

      minimum: 1

Beta Compaction Block

• BetaCompactionBlock object

  A compaction block returned when autocompact is triggered.

  When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

  • type: "compaction"

    default: compaction

  • content: string or null

    Summary of compacted content, or null if compaction failed

  • encrypted_content: string or null

    Opaque metadata from prior compaction, to be round-tripped verbatim

Beta Compaction Block Param

• BetaCompactionBlockParam object

  A compaction block containing summary of previous context.

  Users should round-trip these blocks from responses to subsequent requests to maintain context across compaction boundaries.

  When content is None, the block represents a failed compaction. The server treats these as no-ops. Empty string content is not allowed.

  • type: "compaction"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • content: optional string or null

    Summary of previously compacted content, or null if compaction failed

  • encrypted_content: optional string or null

    Opaque metadata from prior compaction, to be round-tripped verbatim

Beta Compaction Content Block Delta

• BetaCompactionContentBlockDelta object

  • type: "compaction_delta"

    default: compaction_delta

  • content: string or null

  • encrypted_content: string or null

    Opaque metadata from prior compaction, to be round-tripped verbatim

Beta Compaction Iteration Usage

• BetaCompactionIterationUsage object

  Token usage for a compaction iteration.

  • type: "compaction"

    Usage for a compaction iteration

    default: compaction

  • cache_creation: BetaCacheCreation or null

    Breakdown of cached tokens by TTL

    • ephemeral_1h_input_tokens: number

      The number of input tokens used to create the 1 hour cache entry.

      default: 0, minimum: 0

    • ephemeral_5m_input_tokens: number

      The number of input tokens used to create the 5 minute cache entry.

      default: 0, minimum: 0

  • cache_creation_input_tokens: number

    The number of input tokens used to create the cache entry.

    default: 0, minimum: 0

  • cache_read_input_tokens: number

    The number of input tokens read from the cache.

    default: 0, minimum: 0

  • input_tokens: number

    The number of input tokens which were used.

    minimum: 0

  • output_tokens: number

    The number of output tokens which were used.

    minimum: 0

Beta Computer Cursor Position Config

• BetaComputerCursorPositionConfig object

  cursor_position's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Double Click Config

• BetaComputerDoubleClickConfig object

  double_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Hold Key Config

• BetaComputerHoldKeyConfig object

  hold_key's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Key Config

• BetaComputerKeyConfig object

  key's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Left Click Config

• BetaComputerLeftClickConfig object

  left_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Left Click Drag Config

• BetaComputerLeftClickDragConfig object

  left_click_drag's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Left Mouse Down Config

• BetaComputerLeftMouseDownConfig object

  left_mouse_down's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Left Mouse Up Config

• BetaComputerLeftMouseUpConfig object

  left_mouse_up's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Middle Click Config

• BetaComputerMiddleClickConfig object

  middle_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Mouse Move Config

• BetaComputerMouseMoveConfig object

  mouse_move's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Right Click Config

• BetaComputerRightClickConfig object

  right_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Screenshot Config

• BetaComputerScreenshotConfig object

  screenshot's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Scroll Config

• BetaComputerScrollConfig object

  scroll's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Toolset 20260801

• BetaComputerToolset20260801 object

  The computer toolset: a single tools[] entry (carrying no name) that declares the computer tool family. The model is served the family's tool with any members disabled via configs removed from its schema. Every member is enabled by default, zoom included. The single-tool options display_number and enable_zoom are not fields of a toolset entry — it carries only type, configs, and cache_control; zoom is controlled via configs.zoom.enabled.

  • type: "computer_toolset_20260801"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • configs: optional BetaComputerToolsetConfigs or null

    Per-member configuration for computer_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

    • type: optional BetaComputerTypeConfig or null

      type's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • cursor_position: optional BetaComputerCursorPositionConfig or null

      cursor_position's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • double_click: optional BetaComputerDoubleClickConfig or null

      double_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • hold_key: optional BetaComputerHoldKeyConfig or null

      hold_key's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • key: optional BetaComputerKeyConfig or null

      key's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • left_click: optional BetaComputerLeftClickConfig or null

      left_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • left_click_drag: optional BetaComputerLeftClickDragConfig or null

      left_click_drag's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • left_mouse_down: optional BetaComputerLeftMouseDownConfig or null

      left_mouse_down's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • left_mouse_up: optional BetaComputerLeftMouseUpConfig or null

      left_mouse_up's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • middle_click: optional BetaComputerMiddleClickConfig or null

      middle_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • mouse_move: optional BetaComputerMouseMoveConfig or null

      mouse_move's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • right_click: optional BetaComputerRightClickConfig or null

      right_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • screenshot: optional BetaComputerScreenshotConfig or null

      screenshot's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • scroll: optional BetaComputerScrollConfig or null

      scroll's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • triple_click: optional BetaComputerTripleClickConfig or null

      triple_click's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • wait: optional BetaComputerWaitConfig or null

      wait's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

    • zoom: optional BetaComputerZoomConfig or null

      zoom's config overrides.

      • defer_loading: optional boolean or null

        Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

      • enabled: optional boolean or null

        Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Toolset Configs

• BetaComputerToolsetConfigs object

  Per-member configuration for computer_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

  • type: optional BetaComputerTypeConfig or null

    type's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • cursor_position: optional BetaComputerCursorPositionConfig or null

    cursor_position's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • double_click: optional BetaComputerDoubleClickConfig or null

    double_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • hold_key: optional BetaComputerHoldKeyConfig or null

    hold_key's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • key: optional BetaComputerKeyConfig or null

    key's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • left_click: optional BetaComputerLeftClickConfig or null

    left_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • left_click_drag: optional BetaComputerLeftClickDragConfig or null

    left_click_drag's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • left_mouse_down: optional BetaComputerLeftMouseDownConfig or null

    left_mouse_down's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • left_mouse_up: optional BetaComputerLeftMouseUpConfig or null

    left_mouse_up's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • middle_click: optional BetaComputerMiddleClickConfig or null

    middle_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • mouse_move: optional BetaComputerMouseMoveConfig or null

    mouse_move's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • right_click: optional BetaComputerRightClickConfig or null

    right_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • screenshot: optional BetaComputerScreenshotConfig or null

    screenshot's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • scroll: optional BetaComputerScrollConfig or null

    scroll's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • triple_click: optional BetaComputerTripleClickConfig or null

    triple_click's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • wait: optional BetaComputerWaitConfig or null

    wait's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • zoom: optional BetaComputerZoomConfig or null

    zoom's config overrides.

    • defer_loading: optional boolean or null

      Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

    • enabled: optional boolean or null

      Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Triple Click Config

• BetaComputerTripleClickConfig object

  triple_click's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Type Config

• BetaComputerTypeConfig object

  type's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Wait Config

• BetaComputerWaitConfig object

  wait's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Computer Zoom Config

• BetaComputerZoomConfig object

  zoom's config overrides.

  • defer_loading: optional boolean or null

    Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

  • enabled: optional boolean or null

    Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

Beta Container

• BetaContainer object

  Information about the container used in the request (for the code execution tool)

  • id: string

    Identifier for the container used in this request

  • expires_at: string

    The time at which the container will expire.

    format: date-time

  • skills: array of BetaContainerSkill or null

    Skills loaded in the container

    • type: "anthropic" or "custom"

      Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

      • "anthropic"

      • "custom"

    • skill_id: string

      Skill ID

      maxLength: 64, minLength: 1

    • version: string

      The resolved version: a skill version ID for custom skills.

      maxLength: 64, minLength: 1

Beta Container Params

• BetaContainerParams object

  Container parameters with skills to be loaded.

  • id: optional string or null

    Container id

  • skills: optional array of BetaSkillParams or null

    List of skills to load in the container

    maxItems: 20

    • type: "anthropic" or "custom"

      Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

      • "anthropic"

      • "custom"

    • skill_id: string

      Skill ID

      maxLength: 64, minLength: 1

    • version: optional string

      Skill version or 'latest' for most recent version

      maxLength: 64, minLength: 1

Beta Container Skill

• BetaContainerSkill object

  A skill that was loaded in a container (response model).

  • type: "anthropic" or "custom"

    Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

    • "anthropic"

    • "custom"

  • skill_id: string

    Skill ID

    maxLength: 64, minLength: 1

  • version: string

    The resolved version: a skill version ID for custom skills.

    maxLength: 64, minLength: 1

Beta Container Upload Block

• BetaContainerUploadBlock object

  Response model for a file uploaded to the container.

  • type: "container_upload"

    default: container_upload

  • file_id: string

Beta Container Upload Block Param

• BetaContainerUploadBlockParam object

  A content block that represents a file to be uploaded to the container Files uploaded via this block will be available in the container's input directory.

  • type: "container_upload"

  • file_id: string

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta Content Block

• BetaContentBlock = BetaTextBlock or BetaThinkingBlock or BetaRedactedThinkingBlock or 14 more

  Response model for a file uploaded to the container.

  • BetaTextBlock object

    • type: "text"

      default: text

    • citations: array of BetaTextCitation or null

      Citations supporting the text block.

      The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

      • BetaCitationCharLocation object

        • type: "char_location"

          default: char_location

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

        • end_char_index: number

        • file_id: string or null

        • start_char_index: number

          minimum: 0

      • BetaCitationPageLocation object

        • type: "page_location"

          default: page_location

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

        • end_page_number: number

        • file_id: string or null

        • start_page_number: number

          minimum: 1

      • BetaCitationContentBlockLocation object

        • type: "content_block_location"

          default: content_block_location

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • document_index: number

          minimum: 0

        • document_title: string or null

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • file_id: string or null

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

      • BetaCitationsWebSearchResultLocation object

        • type: "web_search_result_location"

          default: web_search_result_location

        • cited_text: string

        • encrypted_index: string

        • title: string or null

          maxLength: 512

        • url: string

      • BetaCitationSearchResultLocation object

        • type: "search_result_location"

          default: search_result_location

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • search_result_index: number

          0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from document_index; server-side web search results are not included in this count.

          minimum: 0

        • source: string

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

        • title: string or null

    • text: string

      minLength: 0

  • BetaThinkingBlock object

    • type: "thinking"

      default: thinking

    • signature: string

      A value used to verify that this thinking block was generated by Claude when it is passed back to the API.

      This is an opaque field and should not be interpreted or parsed. When passing thinking blocks back to the API (required when using tools with extended thinking), pass them back exactly as received, with this field intact.

      See extended thinking for details.

    • thinking: string

      The text of Claude's thinking process for this block.

  • BetaRedactedThinkingBlock object

    • type: "redacted_thinking"

      default: redacted_thinking

    • data: string

      The contents of this redacted thinking block, returned when portions of the model's thinking were safety-redacted. This field is opaque and encrypted, with no readable content.

      Pass redacted_thinking blocks back to the API unchanged when continuing a multi-turn conversation.

      See extended thinking for details.

  • BetaToolUseBlock object

    • type: "tool_use"

      default: tool_use

    • id: string

      pattern: ^[a-zA-Z0-9_-]+$

    • input: map[unknown]

    • name: string

      minLength: 1

    • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

      Tool invocation directly from the model.

      • BetaDirectCaller object

        Tool invocation directly from the model.

        • type: "direct"

      • BetaServerToolCaller object

        Tool invocation generated by a server-side tool.

        • type: "code_execution_20250825"

        • tool_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • BetaServerToolCaller20260120 object

        • type: "code_execution_20260120"

        • tool_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • toolset_name: optional string or null

      For a toolset member tool_use, the toolset family.

      maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

  • BetaServerToolUseBlock object

    • type: "server_tool_use"

      default: server_tool_use

    • id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • input: map[unknown]

    • name: "advisor" or "web_search" or "web_fetch" or 5 more

      • "advisor"

      • "web_search"

      • "web_fetch"

      • "code_execution"

      • "bash_code_execution"

      • "text_editor_code_execution"

      • "tool_search_tool_regex"

      • "tool_search_tool_bm25"

    • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

      Tool invocation directly from the model.

      • BetaDirectCaller object

        Tool invocation directly from the model.

      • BetaServerToolCaller object

        Tool invocation generated by a server-side tool.

      • BetaServerToolCaller20260120 object

  • BetaWebSearchToolResultBlock object

    • type: "web_search_tool_result"

      default: web_search_tool_result

    • content: BetaWebSearchToolResultBlockContent

      • BetaWebSearchToolResultError object

        • type: "web_search_tool_result_error"

          default: web_search_tool_result_error

        • error_code: BetaWebSearchToolResultErrorCode

          • "invalid_tool_input"

          • "unavailable"

          • "max_uses_exceeded"

          • "too_many_requests"

          • "query_too_long"

          • "request_too_large"

      • array of BetaWebSearchResultBlock

        • type: "web_search_result"

          default: web_search_result

        • encrypted_content: string

        • page_age: string or null

        • title: string

        • url: string

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

      Tool invocation directly from the model.

      • BetaDirectCaller object

        Tool invocation directly from the model.

      • BetaServerToolCaller object

        Tool invocation generated by a server-side tool.

      • BetaServerToolCaller20260120 object

  • BetaWebFetchToolResultBlock object

    • type: "web_fetch_tool_result"

      default: web_fetch_tool_result

    • content: BetaWebFetchToolResultErrorBlock or BetaWebFetchBlock

      • BetaWebFetchToolResultErrorBlock object

        • type: "web_fetch_tool_result_error"

          default: web_fetch_tool_result_error

        • error_code: BetaWebFetchToolResultErrorCode

          • "invalid_tool_input"

          • "url_too_long"

          • "url_not_allowed"

          • "url_not_in_prior_context"

          • "url_not_accessible"

          • "unsupported_content_type"

          • "too_many_requests"

          • "max_uses_exceeded"

          • "unavailable"

          • "content_too_large"

      • BetaWebFetchBlock object

        • type: "web_fetch_result"

          default: web_fetch_result

        • content: BetaDocumentBlock

          • type: "document"

            default: document

          • citations: BetaCitationConfig or null

            Citation configuration for the document

            • enabled: boolean

              default: false

          • source: BetaBase64PDFSource or BetaPlainTextSource

            • BetaBase64PDFSource object

              • type: "base64"

              • data: string

                format: byte

              • media_type: "application/pdf"

            • BetaPlainTextSource object

              • type: "text"

              • data: string

              • media_type: "text/plain"

          • title: string or null

            The title of the document

        • retrieved_at: string or null

          ISO 8601 timestamp when the content was retrieved

        • url: string

          Fetched content URL

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

      Tool invocation directly from the model.

      • BetaDirectCaller object

        Tool invocation directly from the model.

      • BetaServerToolCaller object

        Tool invocation generated by a server-side tool.

      • BetaServerToolCaller20260120 object

  • BetaAdvisorToolResultBlock object

    • type: "advisor_tool_result"

      default: advisor_tool_result

    • content: BetaAdvisorToolResultError or BetaAdvisorResultBlock or BetaAdvisorRedactedResultBlock

      • BetaAdvisorToolResultError object

        • type: "advisor_tool_result_error"

          default: advisor_tool_result_error

        • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

          • "max_uses_exceeded"

          • "prompt_too_long"

          • "too_many_requests"

          • "overloaded"

          • "unavailable"

          • "execution_time_exceeded"

          • "model_not_found"

      • BetaAdvisorResultBlock object

        • type: "advisor_result"

          default: advisor_result

        • stop_reason: string or null

          The advisor sub-inference's stop reason (same values as the top-level message stop_reason). max_tokens indicates the advisor's output was truncated at the tool's max_tokens value or the advisor model's policy cap.

        • text: string

      • BetaAdvisorRedactedResultBlock object

        • type: "advisor_redacted_result"

          default: advisor_redacted_result

        • encrypted_content: string

          Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

        • stop_reason: string or null

          The advisor sub-inference's stop reason (same values as the top-level message stop_reason).

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • BetaCodeExecutionToolResultBlock object

    • type: "code_execution_tool_result"

      default: code_execution_tool_result

    • content: BetaCodeExecutionToolResultBlockContent

      Code execution result with encrypted stdout for PFC + web_search results.

      • BetaCodeExecutionToolResultError object

        • type: "code_execution_tool_result_error"

          default: code_execution_tool_result_error

        • error_code: BetaCodeExecutionToolResultErrorCode

          • "invalid_tool_input"

          • "unavailable"

          • "too_many_requests"

          • "execution_time_exceeded"

      • BetaCodeExecutionResultBlock object

        • type: "code_execution_result"

          default: code_execution_result

        • content: array of BetaCodeExecutionOutputBlock

          • type: "code_execution_output"

            default: code_execution_output

          • file_id: string

        • return_code: number

        • stderr: string

        • stdout: string

      • BetaEncryptedCodeExecutionResultBlock object

        Code execution result with encrypted stdout for PFC + web_search results.

        • type: "encrypted_code_execution_result"

          default: encrypted_code_execution_result

        • content: array of BetaCodeExecutionOutputBlock

          • type: "code_execution_output"

            default: code_execution_output

          • file_id: string

        • encrypted_stdout: string

        • return_code: number

        • stderr: string

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • BetaBashCodeExecutionToolResultBlock object

    • type: "bash_code_execution_tool_result"

      default: bash_code_execution_tool_result

    • content: BetaBashCodeExecutionToolResultError or BetaBashCodeExecutionResultBlock

      • BetaBashCodeExecutionToolResultError object

        • type: "bash_code_execution_tool_result_error"

          default: bash_code_execution_tool_result_error

        • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

          • "invalid_tool_input"

          • "unavailable"

          • "too_many_requests"

          • "execution_time_exceeded"

          • "output_file_too_large"

      • BetaBashCodeExecutionResultBlock object

        • type: "bash_code_execution_result"

          default: bash_code_execution_result

        • content: array of BetaBashCodeExecutionOutputBlock

          • type: "bash_code_execution_output"

            default: bash_code_execution_output

          • file_id: string

        • return_code: number

        • stderr: string

        • stdout: string

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • BetaTextEditorCodeExecutionToolResultBlock object

    • type: "text_editor_code_execution_tool_result"

      default: text_editor_code_execution_tool_result

    • content: BetaTextEditorCodeExecutionToolResultError or BetaTextEditorCodeExecutionViewResultBlock or BetaTextEditorCodeExecutionCreateResultBlock or BetaTextEditorCodeExecutionStrReplaceResultBlock

      • BetaTextEditorCodeExecutionToolResultError object

        • type: "text_editor_code_execution_tool_result_error"

          default: text_editor_code_execution_tool_result_error

        • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

          • "invalid_tool_input"

          • "unavailable"

          • "too_many_requests"

          • "execution_time_exceeded"

          • "file_not_found"

        • error_message: string or null

      • BetaTextEditorCodeExecutionViewResultBlock object

        • type: "text_editor_code_execution_view_result"

          default: text_editor_code_execution_view_result

        • content: string

        • file_type: "text" or "image" or "pdf"

          • "text"

          • "image"

          • "pdf"

        • num_lines: number or null

        • start_line: number or null

        • total_lines: number or null

      • BetaTextEditorCodeExecutionCreateResultBlock object

        • type: "text_editor_code_execution_create_result"

          default: text_editor_code_execution_create_result

        • is_file_update: boolean

      • BetaTextEditorCodeExecutionStrReplaceResultBlock object

        • type: "text_editor_code_execution_str_replace_result"

          default: text_editor_code_execution_str_replace_result

        • lines: array of string or null

        • new_lines: number or null

        • new_start: number or null

        • old_lines: number or null

        • old_start: number or null

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • BetaToolSearchToolResultBlock object

    • type: "tool_search_tool_result"

      default: tool_search_tool_result

    • content: BetaToolSearchToolResultError or BetaToolSearchToolSearchResultBlock

      • BetaToolSearchToolResultError object

        • type: "tool_search_tool_result_error"

          default: tool_search_tool_result_error

        • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

          • "invalid_tool_input"

          • "unavailable"

          • "too_many_requests"

          • "execution_time_exceeded"

        • error_message: string or null

      • BetaToolSearchToolSearchResultBlock object

        • type: "tool_search_tool_search_result"

          default: tool_search_tool_search_result

        • tool_references: array of BetaToolReferenceBlock

          • type: "tool_reference"

            default: tool_reference

          • tool_name: string

            maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • BetaMCPToolUseBlock object

    • type: "mcp_tool_use"

      default: mcp_tool_use

    • id: string

      pattern: ^[a-zA-Z0-9_-]+$

    • input: map[unknown]

    • name: string

      The name of the MCP tool

    • server_name: string

      The name of the MCP server

  • BetaMCPToolResultBlock object

    • type: "mcp_tool_result"

      default: mcp_tool_result

    • content: string or array of BetaTextBlock

      • string

      • BetaMCPToolResultBlockContent = array of BetaTextBlock

        • type: "text"

          default: text

        • citations: array of BetaTextCitation or null

          Citations supporting the text block.

          The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

        • text: string

          minLength: 0

    • is_error: boolean

      default: false

    • tool_use_id: string

      pattern: ^[a-zA-Z0-9_-]+$

  • BetaContainerUploadBlock object

    Response model for a file uploaded to the container.

    • type: "container_upload"

      default: container_upload

    • file_id: string

  • BetaCompactionBlock object

    A compaction block returned when autocompact is triggered.

    When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

    • type: "compaction"

      default: compaction

    • content: string or null

      Summary of compacted content, or null if compaction failed

    • encrypted_content: string or null

      Opaque metadata from prior compaction, to be round-tripped verbatim

  • BetaFallbackBlock object

    Marks the point in content where one model's output gives way to the next.

    One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

    The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

    • type: "fallback"

      default: fallback

    • from: BetaFallbackInfo

      The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its model echoes the top-level model string the caller sent (alias or canonical); when the declining hop is a fallback model, its model is that model's canonical id.

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

          The model that will complete your prompt.

          See models for additional details and options.

          • "claude-fable-5-1"

            Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

          • "claude-mythos-5-1"

            Our most capable model for cybersecurity and biology research, available through trusted access programs

          • "claude-sonnet-5"

            High-performance model for coding and agents

          • "claude-fable-5"

            Next generation of intelligence for the hardest knowledge work and coding problems

          • "claude-mythos-5"

            Most capable model for cybersecurity and biology research

          • "claude-opus-5"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-8"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-7"

            Powerful intelligence for long-running agents and coding

          • "claude-mythos-preview"

            New class of intelligence, strongest in coding and cybersecurity

          • "claude-opus-4-6"

            Powerful intelligence for long-running agents and coding

          • "claude-sonnet-4-6"

            Best combination of speed and intelligence

          • "claude-haiku-4-5"

            Fastest model with near-frontier intelligence

          • "claude-haiku-4-5-20251001"

            Fastest model with near-frontier intelligence

          • "claude-opus-4-5"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-5-20251101"

            Powerful intelligence for long-running agents and coding

          • "claude-sonnet-4-5"

            High-performance model for agents and coding

          • "claude-sonnet-4-5-20250929"

            High-performance model for agents and coding

        • string

    • to: BetaFallbackInfo

      The fallback model producing the content that follows this block. Its model is always the canonical id.

    • trigger: BetaFallbackRefusalTrigger

      What caused the from model to hand over at this hop.

      • type: "refusal"

        default: refusal

      • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

        The policy category that triggered a refusal.

        • "cyber"

          The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

        • "bio"

          The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

        • "frontier_llm"

          The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

        • "reasoning_extraction"

          The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

        • "general_harms"

          The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

Beta Content Block Param

• BetaContentBlockParam = BetaTextBlockParam or BetaImageBlockParam or BetaRequestDocumentBlock or 20 more

  Regular text content.

  • BetaTextBlockParam object

    • type: "text"

    • text: string

      minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

      • type: "ephemeral"

      • ttl: optional "5m" or "1h"

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        • 5m: 5 minutes
        • 1h: 1 hour

        Defaults to 5m. See prompt caching pricing for details.

        • "5m"

        • "1h"

    • citations: optional array of BetaTextCitationParam or null

      • BetaCitationCharLocationParam object

        • type: "char_location"

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_char_index: number

        • start_char_index: number

          minimum: 0

      • BetaCitationPageLocationParam object

        • type: "page_location"

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_page_number: number

        • start_page_number: number

          minimum: 1

      • BetaCitationContentBlockLocationParam object

        • type: "content_block_location"

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

      • BetaCitationWebSearchResultLocationParam object

        • type: "web_search_result_location"

        • cited_text: string

        • encrypted_index: string

        • title: string or null

          maxLength: 512, minLength: 1

        • url: string

          minLength: 1

      • BetaCitationSearchResultLocationParam object

        • type: "search_result_location"

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • search_result_index: number

          0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from document_index; server-side web search results are not included in this count.

          minimum: 0

        • source: string

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

        • title: string or null

  • BetaImageBlockParam object

    • type: "image"

    • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

      • BetaBase64ImageSource object

        • type: "base64"

        • data: string

          format: byte

        • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

          • "image/jpeg"

          • "image/png"

          • "image/gif"

          • "image/webp"

      • BetaURLImageSource object

        • type: "url"

        • url: string

      • BetaFileImageSource object

        • type: "file"

        • file_id: string

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • transformations: optional BetaImageTransformationsParam or null

      Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

      • oversized_image: optional "downsize" or "error"

        What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

        • "downsize"

        • "error"

  • BetaRequestDocumentBlock object

    • type: "document"

    • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

      • BetaBase64PDFSource object

        • type: "base64"

        • data: string

          format: byte

        • media_type: "application/pdf"

      • BetaPlainTextSource object

        • type: "text"

        • data: string

        • media_type: "text/plain"

      • BetaContentBlockSource object

        • type: "content"

        • content: string or array of BetaContentBlockSourceContent

          • string

          • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

            • BetaTextBlockParam object

            • BetaImageBlockParam object

      • BetaURLPDFSource object

        • type: "url"

        • url: string

      • BetaFileDocumentSource object

        • type: "file"

        • file_id: string

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      • enabled: optional boolean

    • context: optional string or null

      minLength: 1

    • title: optional string or null

      maxLength: 500, minLength: 1

  • BetaSearchResultBlockParam object

    • type: "search_result"

    • content: array of BetaTextBlockParam

      • type: "text"

      • text: string

        minLength: 1

      • cache_control: optional BetaCacheControlEphemeral or null

        Create a cache control breakpoint at this content block.

      • citations: optional array of BetaTextCitationParam or null

    • source: string

    • title: string

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam

  • BetaThinkingBlockParam object

    • type: "thinking"

    • signature: string

      The signature value of this thinking block, exactly as returned by the API in a previous response. Used to verify that the block was generated by Claude.

      Thinking blocks must be passed back unmodified and in their original order; a modified block results in a 400 invalid_request_error.

    • thinking: string

      The thinking text of this block as returned by the API.

  • BetaRedactedThinkingBlockParam object

    • type: "redacted_thinking"

    • data: string

      The data value of this redacted thinking block, exactly as returned by the API in a previous response. Opaque and encrypted; pass it back unchanged.

  • BetaToolUseBlockParam object

    • type: "tool_use"

    • id: string

      pattern: ^[a-zA-Z0-9_-]+$

    • input: map[unknown]

    • name: string

      maxLength: 200, minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

      Tool invocation directly from the model.

      • BetaDirectCaller object

        Tool invocation directly from the model.

        • type: "direct"

      • BetaServerToolCaller object

        Tool invocation generated by a server-side tool.

        • type: "code_execution_20250825"

        • tool_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • BetaServerToolCaller20260120 object

        • type: "code_execution_20260120"

        • tool_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • toolset_name: optional string or null

      For a toolset member tool_use, the toolset family this member belongs to.

      maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

  • BetaToolResultBlockParam object

    • type: "tool_result"

    • tool_use_id: string

      pattern: ^[a-zA-Z0-9_-]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • content: optional string or array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

      • string

      • array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

        • BetaTextBlockParam object

        • BetaImageBlockParam object

        • BetaSearchResultBlockParam object

        • BetaRequestDocumentBlock object

        • BetaToolReferenceBlockParam object

          Tool reference block that can be included in tool_result content.

          • type: "tool_reference"

          • tool_name: string

            maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

          • cache_control: optional BetaCacheControlEphemeral or null

            Create a cache control breakpoint at this content block.

        • BetaBrowserStateBlockParam object

          The caller's browser state after a browser toolset member call — the full inventory of open tabs, which tab is active, and any side effects (tabs opened, download state changes) the call produced.

          At most one per tool_result, only on a non-error result answering a browser toolset member tool_use. The server renders the model-visible text from it; the model never sees the raw fields.

          • type: "browser_state"

          • tabs: array of BetaBrowserStateTabEntry

            All tabs open in the browser after this call — the full inventory, not a delta. May be empty. Whenever non-empty, exactly one entry carries active: true.

            maxItems: 100

            • tab_id: string

              The caller-assigned identifier for this tab, unique within the inventory.

              maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • title: string

              The title of the page the tab is showing. May be empty.

              maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • url: string

              The URL of the page the tab is showing. May be empty.

              maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • active: optional boolean

              Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

          • cache_control: optional BetaCacheControlEphemeral or null

            Create a cache control breakpoint at this content block.

          • state_changes: optional array of BetaBrowserStateChange or null

            Tabs opened and download state changes during this call. "Nothing to report" is expressed by omitting the field, never by an empty list.

            maxItems: 200, minItems: 1

            • BetaBrowserStateChangeTabOpened object

              A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

              Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

              • type: "tab_opened"

              • tab_id: string

                The tab_id of the opened tab, present in tabs.

                maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • BetaBrowserStateChangeDownloadStarted object

              A file download that started during this call.

              • type: "download_started"

              • download_id: string

                The caller-assigned identifier for this download, stable across the state changes reporting it.

                maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

              • url: string

                The final post-redirect URL the download was served from.

                maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • BetaBrowserStateChangeDownloadCompleted object

              A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

              • type: "download_completed"

              • download_id: string

                The caller-assigned identifier for this download, stable across the state changes reporting it.

                maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

              • url: string

                The final post-redirect URL the download was served from.

                maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

              • path: optional string or null

                Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

                pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

              • size_bytes: optional number or null

                The completed download's size.

                minimum: 0

            • BetaBrowserStateChangeDownloadFailed object

              A file download that failed — or was cancelled — during this call.

              • type: "download_failed"

              • download_id: string

                The caller-assigned identifier for this download, stable across the state changes reporting it.

                maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

              • url: string

                The final post-redirect URL the download was served from.

                maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

              • error: optional string or null

                The failure or cancellation detail, when known.

                pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

    • is_error: optional boolean

    • toolset_name: optional string or null

      For a toolset member tool_result, the toolset family of the paired tool_use.

      maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

  • BetaServerToolUseBlockParam object

    • type: "server_tool_use"

    • id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • input: map[unknown]

    • name: "advisor" or "web_search" or "web_fetch" or 5 more

      • "advisor"

      • "web_search"

      • "web_fetch"

      • "code_execution"

      • "bash_code_execution"

      • "text_editor_code_execution"

      • "tool_search_tool_regex"

      • "tool_search_tool_bm25"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

      Tool invocation directly from the model.

      • BetaDirectCaller object

        Tool invocation directly from the model.

      • BetaServerToolCaller object

        Tool invocation generated by a server-side tool.

      • BetaServerToolCaller20260120 object

  • BetaWebSearchToolResultBlockParam object

    • type: "web_search_tool_result"

    • content: BetaWebSearchToolResultBlockParamContent

      • ResultBlock = array of BetaWebSearchResultBlockParam

        • type: "web_search_result"

        • encrypted_content: string

        • title: string

        • url: string

        • page_age: optional string or null

      • BetaWebSearchToolRequestError object

        • type: "web_search_tool_result_error"

        • error_code: BetaWebSearchToolResultErrorCode

          • "invalid_tool_input"

          • "unavailable"

          • "max_uses_exceeded"

          • "too_many_requests"

          • "query_too_long"

          • "request_too_large"

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

      Tool invocation directly from the model.

      • BetaDirectCaller object

        Tool invocation directly from the model.

      • BetaServerToolCaller object

        Tool invocation generated by a server-side tool.

      • BetaServerToolCaller20260120 object

  • BetaWebFetchToolResultBlockParam object

    • type: "web_fetch_tool_result"

    • content: BetaWebFetchToolResultErrorBlockParam or BetaWebFetchBlockParam

      • BetaWebFetchToolResultErrorBlockParam object

        • type: "web_fetch_tool_result_error"

        • error_code: BetaWebFetchToolResultErrorCode

          • "invalid_tool_input"

          • "url_too_long"

          • "url_not_allowed"

          • "url_not_in_prior_context"

          • "url_not_accessible"

          • "unsupported_content_type"

          • "too_many_requests"

          • "max_uses_exceeded"

          • "unavailable"

          • "content_too_large"

      • BetaWebFetchBlockParam object

        • type: "web_fetch_result"

        • content: BetaRequestDocumentBlock

        • url: string

          Fetched content URL

        • retrieved_at: optional string or null

          ISO 8601 timestamp when the content was retrieved

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

      Tool invocation directly from the model.

      • BetaDirectCaller object

        Tool invocation directly from the model.

      • BetaServerToolCaller object

        Tool invocation generated by a server-side tool.

      • BetaServerToolCaller20260120 object

  • BetaAdvisorToolResultBlockParam object

    • type: "advisor_tool_result"

    • content: BetaAdvisorToolResultErrorParam or BetaAdvisorResultBlockParam or BetaAdvisorRedactedResultBlockParam

      • BetaAdvisorToolResultErrorParam object

        • type: "advisor_tool_result_error"

        • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

          • "max_uses_exceeded"

          • "prompt_too_long"

          • "too_many_requests"

          • "overloaded"

          • "unavailable"

          • "execution_time_exceeded"

          • "model_not_found"

      • BetaAdvisorResultBlockParam object

        • type: "advisor_result"

        • text: string

        • stop_reason: optional string or null

      • BetaAdvisorRedactedResultBlockParam object

        • type: "advisor_redacted_result"

        • encrypted_content: string

          Opaque blob produced by a prior response; must be round-tripped verbatim.

        • stop_reason: optional string or null

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaCodeExecutionToolResultBlockParam object

    • type: "code_execution_tool_result"

    • content: BetaCodeExecutionToolResultBlockParamContent

      Code execution result with encrypted stdout for PFC + web_search results.

      • BetaCodeExecutionToolResultErrorParam object

        • type: "code_execution_tool_result_error"

        • error_code: BetaCodeExecutionToolResultErrorCode

          • "invalid_tool_input"

          • "unavailable"

          • "too_many_requests"

          • "execution_time_exceeded"

      • BetaCodeExecutionResultBlockParam object

        • type: "code_execution_result"

        • content: array of BetaCodeExecutionOutputBlockParam

          • type: "code_execution_output"

          • file_id: string

        • return_code: number

        • stderr: string

        • stdout: string

      • BetaEncryptedCodeExecutionResultBlockParam object

        Code execution result with encrypted stdout for PFC + web_search results.

        • type: "encrypted_code_execution_result"

        • content: array of BetaCodeExecutionOutputBlockParam

          • type: "code_execution_output"

          • file_id: string

        • encrypted_stdout: string

        • return_code: number

        • stderr: string

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaBashCodeExecutionToolResultBlockParam object

    • type: "bash_code_execution_tool_result"

    • content: BetaBashCodeExecutionToolResultErrorParam or BetaBashCodeExecutionResultBlockParam

      • BetaBashCodeExecutionToolResultErrorParam object

        • type: "bash_code_execution_tool_result_error"

        • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

          • "invalid_tool_input"

          • "unavailable"

          • "too_many_requests"

          • "execution_time_exceeded"

          • "output_file_too_large"

      • BetaBashCodeExecutionResultBlockParam object

        • type: "bash_code_execution_result"

        • content: array of BetaBashCodeExecutionOutputBlockParam

          • type: "bash_code_execution_output"

          • file_id: string

        • return_code: number

        • stderr: string

        • stdout: string

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaTextEditorCodeExecutionToolResultBlockParam object

    • type: "text_editor_code_execution_tool_result"

    • content: BetaTextEditorCodeExecutionToolResultErrorParam or BetaTextEditorCodeExecutionViewResultBlockParam or BetaTextEditorCodeExecutionCreateResultBlockParam or BetaTextEditorCodeExecutionStrReplaceResultBlockParam

      • BetaTextEditorCodeExecutionToolResultErrorParam object

        • type: "text_editor_code_execution_tool_result_error"

        • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

          • "invalid_tool_input"

          • "unavailable"

          • "too_many_requests"

          • "execution_time_exceeded"

          • "file_not_found"

        • error_message: optional string or null

      • BetaTextEditorCodeExecutionViewResultBlockParam object

        • type: "text_editor_code_execution_view_result"

        • content: string

        • file_type: "text" or "image" or "pdf"

          • "text"

          • "image"

          • "pdf"

        • num_lines: optional number or null

        • start_line: optional number or null

        • total_lines: optional number or null

      • BetaTextEditorCodeExecutionCreateResultBlockParam object

        • type: "text_editor_code_execution_create_result"

        • is_file_update: boolean

      • BetaTextEditorCodeExecutionStrReplaceResultBlockParam object

        • type: "text_editor_code_execution_str_replace_result"

        • lines: optional array of string or null

        • new_lines: optional number or null

        • new_start: optional number or null

        • old_lines: optional number or null

        • old_start: optional number or null

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaToolSearchToolResultBlockParam object

    • type: "tool_search_tool_result"

    • content: BetaToolSearchToolResultErrorParam or BetaToolSearchToolSearchResultBlockParam

      • BetaToolSearchToolResultErrorParam object

        • type: "tool_search_tool_result_error"

        • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

          • "invalid_tool_input"

          • "unavailable"

          • "too_many_requests"

          • "execution_time_exceeded"

        • error_message: optional string or null

      • BetaToolSearchToolSearchResultBlockParam object

        • type: "tool_search_tool_search_result"

        • tool_references: array of BetaToolReferenceBlockParam

          • type: "tool_reference"

          • tool_name: string

            maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

          • cache_control: optional BetaCacheControlEphemeral or null

            Create a cache control breakpoint at this content block.

    • tool_use_id: string

      pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaMCPToolUseBlockParam object

    • type: "mcp_tool_use"

    • id: string

      pattern: ^[a-zA-Z0-9_-]+$

    • input: map[unknown]

    • name: string

    • server_name: string

      The name of the MCP server

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaRequestMCPToolResultBlockParam object

    • type: "mcp_tool_result"

    • tool_use_id: string

      pattern: ^[a-zA-Z0-9_-]+$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • content: optional string or array of BetaTextBlockParam

      • string

      • BetaMCPToolResultBlockParamContent = array of BetaTextBlockParam

        • type: "text"

        • text: string

          minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional array of BetaTextCitationParam or null

    • is_error: optional boolean

  • BetaContainerUploadBlockParam object

    A content block that represents a file to be uploaded to the container Files uploaded via this block will be available in the container's input directory.

    • type: "container_upload"

    • file_id: string

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaCompactionBlockParam object

    A compaction block containing summary of previous context.

    Users should round-trip these blocks from responses to subsequent requests to maintain context across compaction boundaries.

    When content is None, the block represents a failed compaction. The server treats these as no-ops. Empty string content is not allowed.

    • type: "compaction"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • content: optional string or null

      Summary of previously compacted content, or null if compaction failed

    • encrypted_content: optional string or null

      Opaque metadata from prior compaction, to be round-tripped verbatim

  • BetaRequestToolAdditionBlock object

    Mid-conversation directive to surface a declared tool.

    tool references a tool (or MCP toolset) by name from the request's tools; it is offered to the model from this point in the conversation onward.

    • type: "tool_addition"

    • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

      Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

      • BetaToolChangeToolReference object

        Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

        • type: "tool_reference"

        • name: string

          pattern: ^[a-zA-Z0-9_-]{1,128}$

      • BetaToolChangeMCPToolReference object

        Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

        • type: "mcp_tool_reference"

        • name: string

        • server_name: string

      • BetaToolChangeMCPToolsetReference object

        Reference to every tool in the named MCP server's toolset.

        • type: "mcp_toolset_reference"

        • server_name: string

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaRequestToolRemovalBlock object

    Mid-conversation directive to withdraw a tool.

    tool references a tool (or MCP toolset) by name from the request's tools; it is no longer offered to the model from this point in the conversation onward.

    • type: "tool_removal"

    • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

      Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

      • BetaToolChangeToolReference object

        Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

      • BetaToolChangeMCPToolReference object

        Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

      • BetaToolChangeMCPToolsetReference object

        Reference to every tool in the named MCP server's toolset.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

  • BetaFallbackBlockParam object

    A fallback block echoed back from a prior response.

    Accepted in messages[].content and not rendered into the prompt; not validated against the request's fallbacks chain or top-level model.

    Echo the assistant turn back verbatim, including this block in its original position. The block marks the boundary between content produced before and after a fallback hop, and the server relies on that boundary to validate the turn: when thinking runs flank the boundary, omitting the block merges them into one span the server cannot validate (the request is rejected), and moving it into the middle of a single run is likewise rejected; between non-thinking blocks the block's placement has no validation effect.

    • type: "fallback"

    • from: BetaFallbackInfoParam

      Identifies one hop of a fallback transition.

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

          The model that will complete your prompt.

          See models for additional details and options.

          • "claude-fable-5-1"

            Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

          • "claude-mythos-5-1"

            Our most capable model for cybersecurity and biology research, available through trusted access programs

          • "claude-sonnet-5"

            High-performance model for coding and agents

          • "claude-fable-5"

            Next generation of intelligence for the hardest knowledge work and coding problems

          • "claude-mythos-5"

            Most capable model for cybersecurity and biology research

          • "claude-opus-5"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-8"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-7"

            Powerful intelligence for long-running agents and coding

          • "claude-mythos-preview"

            New class of intelligence, strongest in coding and cybersecurity

          • "claude-opus-4-6"

            Powerful intelligence for long-running agents and coding

          • "claude-sonnet-4-6"

            Best combination of speed and intelligence

          • "claude-haiku-4-5"

            Fastest model with near-frontier intelligence

          • "claude-haiku-4-5-20251001"

            Fastest model with near-frontier intelligence

          • "claude-opus-4-5"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-5-20251101"

            Powerful intelligence for long-running agents and coding

          • "claude-sonnet-4-5"

            High-performance model for agents and coding

          • "claude-sonnet-4-5-20250929"

            High-performance model for agents and coding

        • string

    • to: BetaFallbackInfoParam

      Identifies one hop of a fallback transition.

    • trigger: optional unknown

      The response block's trigger, echoed verbatim. Accepted and ignored by the server; any object or null is allowed.

Beta Content Block Source

• BetaContentBlockSource object

  • type: "content"

  • content: string or array of BetaContentBlockSourceContent

    • string

    • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

      • BetaTextBlockParam object

        • type: "text"

        • text: string

          minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

          • type: "ephemeral"

          • ttl: optional "5m" or "1h"

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            • 5m: 5 minutes
            • 1h: 1 hour

            Defaults to 5m. See prompt caching pricing for details.

            • "5m"

            • "1h"

        • citations: optional array of BetaTextCitationParam or null

          • BetaCitationCharLocationParam object

            • type: "char_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_char_index: number

            • start_char_index: number

              minimum: 0

          • BetaCitationPageLocationParam object

            • type: "page_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_page_number: number

            • start_page_number: number

              minimum: 1

          • BetaCitationContentBlockLocationParam object

            • type: "content_block_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

          • BetaCitationWebSearchResultLocationParam object

            • type: "web_search_result_location"

            • cited_text: string

            • encrypted_index: string

            • title: string or null

              maxLength: 512, minLength: 1

            • url: string

              minLength: 1

          • BetaCitationSearchResultLocationParam object

            • type: "search_result_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • search_result_index: number

              0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from document_index; server-side web search results are not included in this count.

              minimum: 0

            • source: string

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

            • title: string or null

      • BetaImageBlockParam object

        • type: "image"

        • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

          • BetaBase64ImageSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

              • "image/jpeg"

              • "image/png"

              • "image/gif"

              • "image/webp"

          • BetaURLImageSource object

            • type: "url"

            • url: string

          • BetaFileImageSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • transformations: optional BetaImageTransformationsParam or null

          Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

          • oversized_image: optional "downsize" or "error"

            What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

            • "downsize"

            • "error"

Beta Content Block Source Content

• BetaContentBlockSourceContent = BetaTextBlockParam or BetaImageBlockParam

  • BetaTextBlockParam object

    • type: "text"

    • text: string

      minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

      • type: "ephemeral"

      • ttl: optional "5m" or "1h"

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        • 5m: 5 minutes
        • 1h: 1 hour

        Defaults to 5m. See prompt caching pricing for details.

        • "5m"

        • "1h"

    • citations: optional array of BetaTextCitationParam or null

      • BetaCitationCharLocationParam object

        • type: "char_location"

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_char_index: number

        • start_char_index: number

          minimum: 0

      • BetaCitationPageLocationParam object

        • type: "page_location"

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_page_number: number

        • start_page_number: number

          minimum: 1

      • BetaCitationContentBlockLocationParam object

        • type: "content_block_location"

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

      • BetaCitationWebSearchResultLocationParam object

        • type: "web_search_result_location"

        • cited_text: string

        • encrypted_index: string

        • title: string or null

          maxLength: 512, minLength: 1

        • url: string

          minLength: 1

      • BetaCitationSearchResultLocationParam object

        • type: "search_result_location"

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • search_result_index: number

          0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from document_index; server-side web search results are not included in this count.

          minimum: 0

        • source: string

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

        • title: string or null

  • BetaImageBlockParam object

    • type: "image"

    • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

      • BetaBase64ImageSource object

        • type: "base64"

        • data: string

          format: byte

        • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

          • "image/jpeg"

          • "image/png"

          • "image/gif"

          • "image/webp"

      • BetaURLImageSource object

        • type: "url"

        • url: string

      • BetaFileImageSource object

        • type: "file"

        • file_id: string

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • transformations: optional BetaImageTransformationsParam or null

      Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

      • oversized_image: optional "downsize" or "error"

        What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

        • "downsize"

        • "error"

Beta Context Management Config

• BetaContextManagementConfig object

  • edits: optional array of BetaClearToolUses20250919Edit or BetaClearThinking20251015Edit or BetaCompact20260112Edit

    List of context management edits to apply

    minItems: 0

    • BetaClearToolUses20250919Edit object

      • type: "clear_tool_uses_20250919"

      • clear_at_least: optional BetaInputTokensClearAtLeast or null

        Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

        • type: "input_tokens"

        • value: number

          minimum: 0

      • clear_tool_inputs: optional boolean or array of string or null

        Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

        • boolean

        • array of string

      • exclude_tools: optional array of string or null

        Tool names whose uses are preserved from clearing

      • keep: optional BetaToolUsesKeep

        Number of tool uses to retain in the conversation

        • type: "tool_uses"

        • value: number

          minimum: 0

      • trigger: optional BetaInputTokensTrigger or BetaToolUsesTrigger

        Condition that triggers the context management strategy

        • BetaInputTokensTrigger object

          • type: "input_tokens"

          • value: number

            minimum: 1

        • BetaToolUsesTrigger object

          • type: "tool_uses"

          • value: number

            minimum: 1

    • BetaClearThinking20251015Edit object

      • type: "clear_thinking_20251015"

      • keep: optional BetaThinkingTurns or BetaAllThinkingTurns or "all"

        Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

        • BetaThinkingTurns object

          • type: "thinking_turns"

          • value: number

            minimum: 1

        • BetaAllThinkingTurns object

          • type: "all"

        • "all"

    • BetaCompact20260112Edit object

      Automatically compact older context when reaching the configured trigger threshold.

      • type: "compact_20260112"

      • instructions: optional string or null

        Additional instructions for summarization.

      • pause_after_compaction: optional boolean

        Whether to pause after compaction and return the compaction block to the user.

      • trigger: optional BetaInputTokensTrigger or null

        When to trigger compaction. Defaults to 150000 input tokens.

Beta Context Management Response

• BetaContextManagementResponse object

  • applied_edits: array of BetaClearToolUses20250919EditResponse or BetaClearThinking20251015EditResponse

    List of context management edits that were applied.

    • BetaClearToolUses20250919EditResponse object

      • type: "clear_tool_uses_20250919"

        The type of context management edit applied.

        default: clear_tool_uses_20250919

      • cleared_input_tokens: number

        Number of input tokens cleared by this edit.

        minimum: 0

      • cleared_tool_uses: number

        Number of tool uses that were cleared.

        minimum: 0

    • BetaClearThinking20251015EditResponse object

      • type: "clear_thinking_20251015"

        The type of context management edit applied.

        default: clear_thinking_20251015

      • cleared_input_tokens: number

        Number of input tokens cleared by this edit.

        minimum: 0

      • cleared_thinking_turns: number

        Number of thinking turns that were cleared.

        minimum: 0

Beta Count Tokens Context Management Response

• BetaCountTokensContextManagementResponse object

  • original_input_tokens: number

    The original token count before context management was applied

Beta Diagnostics

• BetaDiagnostics object

  Response envelope for request-level diagnostics. Present (possibly null) whenever the caller supplied diagnostics on the request.

  • cache_miss_reason: BetaCacheMissModelChanged or BetaCacheMissSystemChanged or BetaCacheMissToolsChanged or 3 more or null

    Explains why the prompt cache could not fully reuse the prefix from the request identified by diagnostics.previous_message_id. null means diagnosis is still pending — the response was serialized before the background comparison completed.

    • BetaCacheMissModelChanged object

      • type: "model_changed"

        default: model_changed

      • cache_missed_input_tokens: number

        Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

    • BetaCacheMissSystemChanged object

      • type: "system_changed"

        default: system_changed

      • cache_missed_input_tokens: number

        Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

    • BetaCacheMissToolsChanged object

      • type: "tools_changed"

        default: tools_changed

      • cache_missed_input_tokens: number

        Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

    • BetaCacheMissMessagesChanged object

      • type: "messages_changed"

        default: messages_changed

      • cache_missed_input_tokens: number

        Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

    • BetaCacheMissPreviousMessageNotFound object

      • type: "previous_message_not_found"

        default: previous_message_not_found

    • BetaCacheMissUnavailable object

      • type: "unavailable"

        default: unavailable

Beta Diagnostics Param

• BetaDiagnosticsParam object

  Request-level diagnostics. Currently carries the previous response id for prompt-cache divergence reporting.

  • previous_message_id: optional string or null

    The id (msg_...) from this client's previous /v1/messages response. The server compares that request's prompt fingerprint against this one and returns diagnostics.cache_miss_reason when the prompt-cache prefix could not be reused. Pass null on the first turn to opt in without a prior message to compare.

    maxLength: 256

Beta Direct Caller

• BetaDirectCaller object

  Tool invocation directly from the model.

  • type: "direct"

Beta Document Block

• BetaDocumentBlock object

  • type: "document"

    default: document

  • citations: BetaCitationConfig or null

    Citation configuration for the document

    • enabled: boolean

      default: false

  • source: BetaBase64PDFSource or BetaPlainTextSource

    • BetaBase64PDFSource object

      • type: "base64"

      • data: string

        format: byte

      • media_type: "application/pdf"

    • BetaPlainTextSource object

      • type: "text"

      • data: string

      • media_type: "text/plain"

  • title: string or null

    The title of the document

Beta Encrypted Code Execution Result Block

• BetaEncryptedCodeExecutionResultBlock object

  Code execution result with encrypted stdout for PFC + web_search results.

  • type: "encrypted_code_execution_result"

    default: encrypted_code_execution_result

  • content: array of BetaCodeExecutionOutputBlock

    • type: "code_execution_output"

      default: code_execution_output

    • file_id: string

  • encrypted_stdout: string

  • return_code: number

  • stderr: string

Beta Encrypted Code Execution Result Block Param

• BetaEncryptedCodeExecutionResultBlockParam object

  Code execution result with encrypted stdout for PFC + web_search results.

  • type: "encrypted_code_execution_result"

  • content: array of BetaCodeExecutionOutputBlockParam

    • type: "code_execution_output"

    • file_id: string

  • encrypted_stdout: string

  • return_code: number

  • stderr: string

Beta Fallback Block

• BetaFallbackBlock object

  Marks the point in content where one model's output gives way to the next.

  One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

  The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

  • type: "fallback"

    default: fallback

  • from: BetaFallbackInfo

    The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its model echoes the top-level model string the caller sent (alias or canonical); when the declining hop is a fallback model, its model is that model's canonical id.

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1"

          Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

        • "claude-mythos-5-1"

          Our most capable model for cybersecurity and biology research, available through trusted access programs

        • "claude-sonnet-5"

          High-performance model for coding and agents

        • "claude-fable-5"

          Next generation of intelligence for the hardest knowledge work and coding problems

        • "claude-mythos-5"

          Most capable model for cybersecurity and biology research

        • "claude-opus-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-8"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-7"

          Powerful intelligence for long-running agents and coding

        • "claude-mythos-preview"

          New class of intelligence, strongest in coding and cybersecurity

        • "claude-opus-4-6"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-6"

          Best combination of speed and intelligence

        • "claude-haiku-4-5"

          Fastest model with near-frontier intelligence

        • "claude-haiku-4-5-20251001"

          Fastest model with near-frontier intelligence

        • "claude-opus-4-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-5-20251101"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-5"

          High-performance model for agents and coding

        • "claude-sonnet-4-5-20250929"

          High-performance model for agents and coding

      • string

  • to: BetaFallbackInfo

    The fallback model producing the content that follows this block. Its model is always the canonical id.

  • trigger: BetaFallbackRefusalTrigger

    What caused the from model to hand over at this hop.

    • type: "refusal"

      default: refusal

    • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

      The policy category that triggered a refusal.

      • "cyber"

        The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

      • "bio"

        The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

      • "frontier_llm"

        The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

      • "reasoning_extraction"

        The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

      • "general_harms"

        The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

Beta Fallback Block Param

• BetaFallbackBlockParam object

  A fallback block echoed back from a prior response.

  Accepted in messages[].content and not rendered into the prompt; not validated against the request's fallbacks chain or top-level model.

  Echo the assistant turn back verbatim, including this block in its original position. The block marks the boundary between content produced before and after a fallback hop, and the server relies on that boundary to validate the turn: when thinking runs flank the boundary, omitting the block merges them into one span the server cannot validate (the request is rejected), and moving it into the middle of a single run is likewise rejected; between non-thinking blocks the block's placement has no validation effect.

  • type: "fallback"

  • from: BetaFallbackInfoParam

    Identifies one hop of a fallback transition.

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1"

          Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

        • "claude-mythos-5-1"

          Our most capable model for cybersecurity and biology research, available through trusted access programs

        • "claude-sonnet-5"

          High-performance model for coding and agents

        • "claude-fable-5"

          Next generation of intelligence for the hardest knowledge work and coding problems

        • "claude-mythos-5"

          Most capable model for cybersecurity and biology research

        • "claude-opus-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-8"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-7"

          Powerful intelligence for long-running agents and coding

        • "claude-mythos-preview"

          New class of intelligence, strongest in coding and cybersecurity

        • "claude-opus-4-6"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-6"

          Best combination of speed and intelligence

        • "claude-haiku-4-5"

          Fastest model with near-frontier intelligence

        • "claude-haiku-4-5-20251001"

          Fastest model with near-frontier intelligence

        • "claude-opus-4-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-5-20251101"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-5"

          High-performance model for agents and coding

        • "claude-sonnet-4-5-20250929"

          High-performance model for agents and coding

      • string

  • to: BetaFallbackInfoParam

    Identifies one hop of a fallback transition.

  • trigger: optional unknown

    The response block's trigger, echoed verbatim. Accepted and ignored by the server; any object or null is allowed.

Beta Fallback Credit Not Applied

• BetaFallbackCreditNotApplied object

  No reprice was applied; reason says why.

  • type: "not_applied"

    default: not_applied

  • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

    Why the reprice was not applied.

    A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

    • "body_mismatch"

    • "continuation_excluded"

    • "continuation_only"

    • "expired"

    • "invalid_target_model"

    • "not_enabled"

    • "reprice_unavailable"

    • "temporarily_unavailable"

    • "variant_fields_present"

    • "wrong_organization"

    • "wrong_platform"

    • "wrong_workspace"

  • remove_to_redeem: optional array of string or null

    Request fields to remove before retrying, so the retry can redeem this token.

    Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

Beta Fallback Credit Redeemed

• BetaFallbackCreditRedeemed object

  The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

  • type: "redeemed"

    default: redeemed

Beta Fallback Credit Token Param

• BetaFallbackCreditTokenParam object

  Object form of fallback_credit_token: the token plus a redemption mode.

  Requires anthropic-beta: fallback-credit-2026-07-01; without that header the field accepts the bare string only. The bare string and the mode-less object are equivalent (both select strict), so wrapping an existing token changes nothing by itself.

  • token: string

    The opaque fallback_credit_token from a prior refusal's stop_details — the same string the bare-string form carries.

    maxLength: 2048, minLength: 1

  • mode: optional "strict" or "best_effort"

    How a failing token affects the retry. strict (the default, and the bare-string behavior): a failing redemption is a 400 and the retry is not served. best_effort: the retry is served either way — a token-layer failure no longer rejects the request; the retry proceeds at normal price and the outcome is reported on the response's usage.fallback_credit. Two failures stay hard in both modes: a malformed token, and combining fallback_credit_token with fallbacks.

    • "strict"

    • "best_effort"

Beta Fallback Credit Usage

• BetaFallbackCreditUsage object

  Outcome of the fallback_credit_token presented on this request.

  • status: BetaFallbackCreditRedeemed or BetaFallbackCreditNotApplied

    Whether the fallback-credit reprice was applied to this response's billing.

    A union discriminated on type. redeemed: the retry is billed as if the conversation had been on the retry model all along — including when the resulting shift is zero because there was nothing to move. not_applied: no reprice was applied; the arm's reason says why.

    • BetaFallbackCreditRedeemed object

      The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

      • type: "redeemed"

        default: redeemed

    • BetaFallbackCreditNotApplied object

      No reprice was applied; reason says why.

      • type: "not_applied"

        default: not_applied

      • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

        Why the reprice was not applied.

        A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

        • "body_mismatch"

        • "continuation_excluded"

        • "continuation_only"

        • "expired"

        • "invalid_target_model"

        • "not_enabled"

        • "reprice_unavailable"

        • "temporarily_unavailable"

        • "variant_fields_present"

        • "wrong_organization"

        • "wrong_platform"

        • "wrong_workspace"

      • remove_to_redeem: optional array of string or null

        Request fields to remove before retrying, so the retry can redeem this token.

        Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

Beta Fallback Info

• BetaFallbackInfo object

  Identifies one hop of a fallback transition.

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1"

        Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

      • "claude-mythos-5-1"

        Our most capable model for cybersecurity and biology research, available through trusted access programs

      • "claude-sonnet-5"

        High-performance model for coding and agents

      • "claude-fable-5"

        Next generation of intelligence for the hardest knowledge work and coding problems

      • "claude-mythos-5"

        Most capable model for cybersecurity and biology research

      • "claude-opus-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-8"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-7"

        Powerful intelligence for long-running agents and coding

      • "claude-mythos-preview"

        New class of intelligence, strongest in coding and cybersecurity

      • "claude-opus-4-6"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-6"

        Best combination of speed and intelligence

      • "claude-haiku-4-5"

        Fastest model with near-frontier intelligence

      • "claude-haiku-4-5-20251001"

        Fastest model with near-frontier intelligence

      • "claude-opus-4-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-5-20251101"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-5"

        High-performance model for agents and coding

      • "claude-sonnet-4-5-20250929"

        High-performance model for agents and coding

    • string

Beta Fallback Info Param

• BetaFallbackInfoParam object

  Identifies one hop of a fallback transition.

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1"

        Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

      • "claude-mythos-5-1"

        Our most capable model for cybersecurity and biology research, available through trusted access programs

      • "claude-sonnet-5"

        High-performance model for coding and agents

      • "claude-fable-5"

        Next generation of intelligence for the hardest knowledge work and coding problems

      • "claude-mythos-5"

        Most capable model for cybersecurity and biology research

      • "claude-opus-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-8"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-7"

        Powerful intelligence for long-running agents and coding

      • "claude-mythos-preview"

        New class of intelligence, strongest in coding and cybersecurity

      • "claude-opus-4-6"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-6"

        Best combination of speed and intelligence

      • "claude-haiku-4-5"

        Fastest model with near-frontier intelligence

      • "claude-haiku-4-5-20251001"

        Fastest model with near-frontier intelligence

      • "claude-opus-4-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-5-20251101"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-5"

        High-performance model for agents and coding

      • "claude-sonnet-4-5-20250929"

        High-performance model for agents and coding

    • string

Beta Fallback Message Iteration Usage

• BetaFallbackMessageIterationUsage object

  Token usage for the fallback-model attempt of a server-side fallback request.

  Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

  • type: "fallback_message"

    Usage for the fallback-model attempt that served the response

    default: fallback_message

  • cache_creation: BetaCacheCreation or null

    Breakdown of cached tokens by TTL

    • ephemeral_1h_input_tokens: number

      The number of input tokens used to create the 1 hour cache entry.

      default: 0, minimum: 0

    • ephemeral_5m_input_tokens: number

      The number of input tokens used to create the 5 minute cache entry.

      default: 0, minimum: 0

  • cache_creation_input_tokens: number

    The number of input tokens used to create the cache entry.

    default: 0, minimum: 0

  • cache_read_input_tokens: number

    The number of input tokens read from the cache.

    default: 0, minimum: 0

  • input_tokens: number

    The number of input tokens which were used.

    minimum: 0

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1"

        Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

      • "claude-mythos-5-1"

        Our most capable model for cybersecurity and biology research, available through trusted access programs

      • "claude-sonnet-5"

        High-performance model for coding and agents

      • "claude-fable-5"

        Next generation of intelligence for the hardest knowledge work and coding problems

      • "claude-mythos-5"

        Most capable model for cybersecurity and biology research

      • "claude-opus-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-8"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-7"

        Powerful intelligence for long-running agents and coding

      • "claude-mythos-preview"

        New class of intelligence, strongest in coding and cybersecurity

      • "claude-opus-4-6"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-6"

        Best combination of speed and intelligence

      • "claude-haiku-4-5"

        Fastest model with near-frontier intelligence

      • "claude-haiku-4-5-20251001"

        Fastest model with near-frontier intelligence

      • "claude-opus-4-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-5-20251101"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-5"

        High-performance model for agents and coding

      • "claude-sonnet-4-5-20250929"

        High-performance model for agents and coding

    • string

  • output_tokens: number

    The number of output tokens which were used.

    minimum: 0

Beta Fallback Param

• BetaFallbackParam object

  One entry in the fallbacks chain on a /v1/messages request.

  model is required. The override fields (max_tokens, thinking, output_config, and speed) set the corresponding parameter for this attempt only and are validated as if the request were made to model. Any other key is rejected at parse time.

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1"

        Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

      • "claude-mythos-5-1"

        Our most capable model for cybersecurity and biology research, available through trusted access programs

      • "claude-sonnet-5"

        High-performance model for coding and agents

      • "claude-fable-5"

        Next generation of intelligence for the hardest knowledge work and coding problems

      • "claude-mythos-5"

        Most capable model for cybersecurity and biology research

      • "claude-opus-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-8"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-7"

        Powerful intelligence for long-running agents and coding

      • "claude-mythos-preview"

        New class of intelligence, strongest in coding and cybersecurity

      • "claude-opus-4-6"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-6"

        Best combination of speed and intelligence

      • "claude-haiku-4-5"

        Fastest model with near-frontier intelligence

      • "claude-haiku-4-5-20251001"

        Fastest model with near-frontier intelligence

      • "claude-opus-4-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-5-20251101"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-5"

        High-performance model for agents and coding

      • "claude-sonnet-4-5-20250929"

        High-performance model for agents and coding

    • string

  • max_tokens: optional number or null

  • output_config: optional BetaOutputConfig or null

    • effort: optional "low" or "medium" or "high" or 2 more or null

      All possible effort levels.

      • "low"

      • "medium"

      • "high"

      • "xhigh"

      • "max"

    • format: optional BetaJSONOutputFormat or null

      A schema to specify Claude's output format in responses. See structured outputs

      • type: "json_schema"

      • schema: map[unknown]

        The JSON schema of the format

    • task_budget: optional BetaTokenTaskBudget or null

      User-configurable total token budget across contexts.

      • type: "tokens"

        The budget type. Currently only 'tokens' is supported.

      • total: number

        Total token budget across all contexts in the session.

        minimum: 1024

      • remaining: optional number or null

        Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

        minimum: 0

  • speed: optional "standard" or "fast" or null

    Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

    • "standard"

    • "fast"

  • thinking: optional BetaThinkingConfigEnabled or BetaThinkingConfigDisabled or BetaThinkingConfigAdaptive or null

    • BetaThinkingConfigEnabled object

      • type: "enabled"

      • budget_tokens: number

        Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

        Must be ≥1024 and less than max_tokens.

        See extended thinking for details.

        minimum: 1024

      • block_binding: optional BetaThinkingBlockBinding or null

        Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

        • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

          What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

          • "error"

          • "drop_block"

      • display: optional "summarized" or "omitted" or "updates" or null

        Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

        • "summarized"

        • "omitted"

        • "updates"

    • BetaThinkingConfigDisabled object

      • type: "disabled"

    • BetaThinkingConfigAdaptive object

      • type: "adaptive"

      • block_binding: optional BetaThinkingBlockBinding or null

        Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

      • display: optional "summarized" or "omitted" or "updates" or null

        Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

        • "summarized"

        • "omitted"

        • "updates"

Beta Fallback Refusal Trigger

• BetaFallbackRefusalTrigger object

  The from model declined for policy reasons.

  • type: "refusal"

    default: refusal

  • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

    The policy category that triggered a refusal.

    • "cyber"

      The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

    • "bio"

      The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

    • "frontier_llm"

      The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

    • "reasoning_extraction"

      The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

    • "general_harms"

      The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

Beta Fallbacks Param

• BetaFallbacksParam = array of BetaFallbackParam or "default"

  Opt-in server-side retry on one or more substitute models when the requested model declines for policy reasons. Tried in order: if the first entry also declines, the second is tried, and so on. The string "default" requests the requested model's server-defined default fallback configuration.

  • array of BetaFallbackParam

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1"

          Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

        • "claude-mythos-5-1"

          Our most capable model for cybersecurity and biology research, available through trusted access programs

        • "claude-sonnet-5"

          High-performance model for coding and agents

        • "claude-fable-5"

          Next generation of intelligence for the hardest knowledge work and coding problems

        • "claude-mythos-5"

          Most capable model for cybersecurity and biology research

        • "claude-opus-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-8"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-7"

          Powerful intelligence for long-running agents and coding

        • "claude-mythos-preview"

          New class of intelligence, strongest in coding and cybersecurity

        • "claude-opus-4-6"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-6"

          Best combination of speed and intelligence

        • "claude-haiku-4-5"

          Fastest model with near-frontier intelligence

        • "claude-haiku-4-5-20251001"

          Fastest model with near-frontier intelligence

        • "claude-opus-4-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-5-20251101"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-5"

          High-performance model for agents and coding

        • "claude-sonnet-4-5-20250929"

          High-performance model for agents and coding

      • string

    • max_tokens: optional number or null

    • output_config: optional BetaOutputConfig or null

      • effort: optional "low" or "medium" or "high" or 2 more or null

        All possible effort levels.

        • "low"

        • "medium"

        • "high"

        • "xhigh"

        • "max"

      • format: optional BetaJSONOutputFormat or null

        A schema to specify Claude's output format in responses. See structured outputs

        • type: "json_schema"

        • schema: map[unknown]

          The JSON schema of the format

      • task_budget: optional BetaTokenTaskBudget or null

        User-configurable total token budget across contexts.

        • type: "tokens"

          The budget type. Currently only 'tokens' is supported.

        • total: number

          Total token budget across all contexts in the session.

          minimum: 1024

        • remaining: optional number or null

          Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

          minimum: 0

    • speed: optional "standard" or "fast" or null

      Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

      • "standard"

      • "fast"

    • thinking: optional BetaThinkingConfigEnabled or BetaThinkingConfigDisabled or BetaThinkingConfigAdaptive or null

      • BetaThinkingConfigEnabled object

        • type: "enabled"

        • budget_tokens: number

          Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

          Must be ≥1024 and less than max_tokens.

          See extended thinking for details.

          minimum: 1024

        • block_binding: optional BetaThinkingBlockBinding or null

          Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

          • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

            What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

            • "error"

            • "drop_block"

        • display: optional "summarized" or "omitted" or "updates" or null

          Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

          • "summarized"

          • "omitted"

          • "updates"

      • BetaThinkingConfigDisabled object

        • type: "disabled"

      • BetaThinkingConfigAdaptive object

        • type: "adaptive"

        • block_binding: optional BetaThinkingBlockBinding or null

          Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

        • display: optional "summarized" or "omitted" or "updates" or null

          Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

          • "summarized"

          • "omitted"

          • "updates"

  • Default = "default"

Beta File Document Source

• BetaFileDocumentSource object

  • type: "file"

  • file_id: string

Beta File Image Source

• BetaFileImageSource object

  • type: "file"

  • file_id: string

Beta Image Block Param

• BetaImageBlockParam object

  • type: "image"

  • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

    • BetaBase64ImageSource object

      • type: "base64"

      • data: string

        format: byte

      • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

        • "image/jpeg"

        • "image/png"

        • "image/gif"

        • "image/webp"

    • BetaURLImageSource object

      • type: "url"

      • url: string

    • BetaFileImageSource object

      • type: "file"

      • file_id: string

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • transformations: optional BetaImageTransformationsParam or null

    Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

    • oversized_image: optional "downsize" or "error"

      What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

      • "downsize"

      • "error"

Beta Image Transformations Param

• BetaImageTransformationsParam object

  Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

  • oversized_image: optional "downsize" or "error"

    What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

    • "downsize"

    • "error"

Beta Input JSON Delta

• BetaInputJSONDelta object

  • type: "input_json_delta"

    default: input_json_delta

  • partial_json: string

Beta Input Tokens Clear At Least

• BetaInputTokensClearAtLeast object

  • type: "input_tokens"

  • value: number

    minimum: 0

Beta Input Tokens Trigger

• BetaInputTokensTrigger object

  • type: "input_tokens"

  • value: number

    minimum: 1

Beta Iterations Usage

• BetaIterationsUsage = array of BetaMessageIterationUsage or BetaCompactionIterationUsage or BetaAdvisorMessageIterationUsage or BetaFallbackMessageIterationUsage

  Per-iteration token usage breakdown.

  Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

  • Determine which iterations exceeded long context thresholds (>=200k tokens)
  • Calculate the context window size from the last message entry
  • Understand token accumulation across server-side tool use loops

  A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

  • BetaMessageIterationUsage object

    Token usage for a sampling iteration.

    • type: "message"

      Usage for a sampling iteration

      default: message

    • cache_creation: BetaCacheCreation or null

      Breakdown of cached tokens by TTL

      • ephemeral_1h_input_tokens: number

        The number of input tokens used to create the 1 hour cache entry.

        default: 0, minimum: 0

      • ephemeral_5m_input_tokens: number

        The number of input tokens used to create the 5 minute cache entry.

        default: 0, minimum: 0

    • cache_creation_input_tokens: number

      The number of input tokens used to create the cache entry.

      default: 0, minimum: 0

    • cache_read_input_tokens: number

      The number of input tokens read from the cache.

      default: 0, minimum: 0

    • input_tokens: number

      The number of input tokens which were used.

      minimum: 0

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1"

          Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

        • "claude-mythos-5-1"

          Our most capable model for cybersecurity and biology research, available through trusted access programs

        • "claude-sonnet-5"

          High-performance model for coding and agents

        • "claude-fable-5"

          Next generation of intelligence for the hardest knowledge work and coding problems

        • "claude-mythos-5"

          Most capable model for cybersecurity and biology research

        • "claude-opus-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-8"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-7"

          Powerful intelligence for long-running agents and coding

        • "claude-mythos-preview"

          New class of intelligence, strongest in coding and cybersecurity

        • "claude-opus-4-6"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-6"

          Best combination of speed and intelligence

        • "claude-haiku-4-5"

          Fastest model with near-frontier intelligence

        • "claude-haiku-4-5-20251001"

          Fastest model with near-frontier intelligence

        • "claude-opus-4-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-5-20251101"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-5"

          High-performance model for agents and coding

        • "claude-sonnet-4-5-20250929"

          High-performance model for agents and coding

      • string

    • output_tokens: number

      The number of output tokens which were used.

      minimum: 0

  • BetaCompactionIterationUsage object

    Token usage for a compaction iteration.

    • type: "compaction"

      Usage for a compaction iteration

      default: compaction

    • cache_creation: BetaCacheCreation or null

      Breakdown of cached tokens by TTL

    • cache_creation_input_tokens: number

      The number of input tokens used to create the cache entry.

      default: 0, minimum: 0

    • cache_read_input_tokens: number

      The number of input tokens read from the cache.

      default: 0, minimum: 0

    • input_tokens: number

      The number of input tokens which were used.

      minimum: 0

    • output_tokens: number

      The number of output tokens which were used.

      minimum: 0

  • BetaAdvisorMessageIterationUsage object

    Token usage for an advisor sub-inference iteration.

    • type: "advisor_message"

      Usage for an advisor sub-inference iteration

      default: advisor_message

    • cache_creation: BetaCacheCreation or null

      Breakdown of cached tokens by TTL

    • cache_creation_input_tokens: number

      The number of input tokens used to create the cache entry.

      default: 0, minimum: 0

    • cache_read_input_tokens: number

      The number of input tokens read from the cache.

      default: 0, minimum: 0

    • input_tokens: number

      The number of input tokens which were used.

      minimum: 0

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

    • output_tokens: number

      The number of output tokens which were used.

      minimum: 0

  • BetaFallbackMessageIterationUsage object

    Token usage for the fallback-model attempt of a server-side fallback request.

    Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

    • type: "fallback_message"

      Usage for the fallback-model attempt that served the response

      default: fallback_message

    • cache_creation: BetaCacheCreation or null

      Breakdown of cached tokens by TTL

    • cache_creation_input_tokens: number

      The number of input tokens used to create the cache entry.

      default: 0, minimum: 0

    • cache_read_input_tokens: number

      The number of input tokens read from the cache.

      default: 0, minimum: 0

    • input_tokens: number

      The number of input tokens which were used.

      minimum: 0

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

    • output_tokens: number

      The number of output tokens which were used.

      minimum: 0

Beta JSON Output Format

• BetaJSONOutputFormat object

  • type: "json_schema"

  • schema: map[unknown]

    The JSON schema of the format

Beta MCP Tool Config

• BetaMCPToolConfig object

  Configuration for a specific tool in an MCP toolset.

  • defer_loading: optional boolean

  • enabled: optional boolean

Beta MCP Tool Default Config

• BetaMCPToolDefaultConfig object

  Default configuration for tools in an MCP toolset.

  • defer_loading: optional boolean

  • enabled: optional boolean

Beta MCP Tool Result Block

• BetaMCPToolResultBlock object

  • type: "mcp_tool_result"

    default: mcp_tool_result

  • content: string or array of BetaTextBlock

    • string

    • BetaMCPToolResultBlockContent = array of BetaTextBlock

      • type: "text"

        default: text

      • citations: array of BetaTextCitation or null

        Citations supporting the text block.

        The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

        • BetaCitationCharLocation object

          • type: "char_location"

            default: char_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_char_index: number

          • file_id: string or null

          • start_char_index: number

            minimum: 0

        • BetaCitationPageLocation object

          • type: "page_location"

            default: page_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_page_number: number

          • file_id: string or null

          • start_page_number: number

            minimum: 1

        • BetaCitationContentBlockLocation object

          • type: "content_block_location"

            default: content_block_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • file_id: string or null

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

        • BetaCitationsWebSearchResultLocation object

          • type: "web_search_result_location"

            default: web_search_result_location

          • cited_text: string

          • encrypted_index: string

          • title: string or null

            maxLength: 512

          • url: string

        • BetaCitationSearchResultLocation object

          • type: "search_result_location"

            default: search_result_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • search_result_index: number

            0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from document_index; server-side web search results are not included in this count.

            minimum: 0

          • source: string

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

          • title: string or null

      • text: string

        minLength: 0

  • is_error: boolean

    default: false

  • tool_use_id: string

    pattern: ^[a-zA-Z0-9_-]+$

Beta MCP Tool Use Block

• BetaMCPToolUseBlock object

  • type: "mcp_tool_use"

    default: mcp_tool_use

  • id: string

    pattern: ^[a-zA-Z0-9_-]+$

  • input: map[unknown]

  • name: string

    The name of the MCP tool

  • server_name: string

    The name of the MCP server

Beta MCP Tool Use Block Param

• BetaMCPToolUseBlockParam object

  • type: "mcp_tool_use"

  • id: string

    pattern: ^[a-zA-Z0-9_-]+$

  • input: map[unknown]

  • name: string

  • server_name: string

    The name of the MCP server

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta MCP Toolset

• BetaMCPToolset object

  Configuration for a group of tools from an MCP server.

  Allows configuring enabled status and defer_loading for all tools from an MCP server, with optional per-tool overrides.

  • type: "mcp_toolset"

  • mcp_server_name: string

    Name of the MCP server to configure tools for

    maxLength: 255, minLength: 1

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • configs: optional map[BetaMCPToolConfig] or null

    Configuration overrides for specific tools, keyed by tool name

    • defer_loading: optional boolean

    • enabled: optional boolean

  • default_config: optional BetaMCPToolDefaultConfig

    Default configuration applied to all tools from this server

    • defer_loading: optional boolean

    • enabled: optional boolean

Beta Memory Tool 20250818

• BetaMemoryTool20250818 object

  • type: "memory_20250818"

  • name: "memory"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Memory Tool 20250818 Command

• BetaMemoryTool20250818Command = BetaMemoryTool20250818ViewCommand or BetaMemoryTool20250818CreateCommand or BetaMemoryTool20250818StrReplaceCommand or 3 more

  • BetaMemoryTool20250818ViewCommand object

    • command: "view"

      Command type identifier

      default: view

    • path: string

      Path to directory or file to view

    • view_range: optional array of number

      Optional line range for viewing specific lines

      minItems: 2, maxItems: 2

  • BetaMemoryTool20250818CreateCommand object

    • command: "create"

      Command type identifier

      default: create

    • file_text: string

      Content to write to the file

    • path: string

      Path where the file should be created

  • BetaMemoryTool20250818StrReplaceCommand object

    • command: "str_replace"

      Command type identifier

      default: str_replace

    • new_str: string

      Text to replace with

    • old_str: string

      Text to search for and replace

    • path: string

      Path to the file where text should be replaced

  • BetaMemoryTool20250818InsertCommand object

    • command: "insert"

      Command type identifier

      default: insert

    • insert_line: number

      Line number where text should be inserted

      minimum: 1

    • insert_text: string

      Text to insert at the specified line

    • path: string

      Path to the file where text should be inserted

  • BetaMemoryTool20250818DeleteCommand object

    • command: "delete"

      Command type identifier

      default: delete

    • path: string

      Path to the file or directory to delete

  • BetaMemoryTool20250818RenameCommand object

    • command: "rename"

      Command type identifier

      default: rename

    • new_path: string

      New path for the file or directory

    • old_path: string

      Current path of the file or directory

Beta Memory Tool 20250818 Create Command

• BetaMemoryTool20250818CreateCommand object

  • command: "create"

    Command type identifier

    default: create

  • file_text: string

    Content to write to the file

  • path: string

    Path where the file should be created

Beta Memory Tool 20250818 Delete Command

• BetaMemoryTool20250818DeleteCommand object

  • command: "delete"

    Command type identifier

    default: delete

  • path: string

    Path to the file or directory to delete

Beta Memory Tool 20250818 Insert Command

• BetaMemoryTool20250818InsertCommand object

  • command: "insert"

    Command type identifier

    default: insert

  • insert_line: number

    Line number where text should be inserted

    minimum: 1

  • insert_text: string

    Text to insert at the specified line

  • path: string

    Path to the file where text should be inserted

Beta Memory Tool 20250818 Rename Command

• BetaMemoryTool20250818RenameCommand object

  • command: "rename"

    Command type identifier

    default: rename

  • new_path: string

    New path for the file or directory

  • old_path: string

    Current path of the file or directory

Beta Memory Tool 20250818 Str Replace Command

• BetaMemoryTool20250818StrReplaceCommand object

  • command: "str_replace"

    Command type identifier

    default: str_replace

  • new_str: string

    Text to replace with

  • old_str: string

    Text to search for and replace

  • path: string

    Path to the file where text should be replaced

Beta Memory Tool 20250818 View Command

• BetaMemoryTool20250818ViewCommand object

  • command: "view"

    Command type identifier

    default: view

  • path: string

    Path to directory or file to view

  • view_range: optional array of number

    Optional line range for viewing specific lines

    minItems: 2, maxItems: 2

Beta Message

• BetaMessage object

  • type: "message"

    Object type.

    For Messages, this is always "message".

    default: message

  • id: string

    Unique object identifier.

    The format and length of IDs may change over time.

  • container: BetaContainer or null

    Information about the container used in the request (for the code execution tool)

    • id: string

      Identifier for the container used in this request

    • expires_at: string

      The time at which the container will expire.

      format: date-time

    • skills: array of BetaContainerSkill or null

      Skills loaded in the container

      • type: "anthropic" or "custom"

        Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

        • "anthropic"

        • "custom"

      • skill_id: string

        Skill ID

        maxLength: 64, minLength: 1

      • version: string

        The resolved version: a skill version ID for custom skills.

        maxLength: 64, minLength: 1

  • content: array of BetaContentBlock

    Content generated by the model.

    This is an array of content blocks, each of which has a type that determines its shape.

    Example:

    [\{"type": "text", "text": "Hi, I'm Claude."\}]

    If the request input messages ended with an assistant turn, then the response content will continue directly from that last turn. You can use this to constrain the model's output.

    For example, if the input messages were:

    [
      \{"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"\},
      \{"role": "assistant", "content": "The best answer is ("\}
    ]

    Then the response content might be:

    [\{"type": "text", "text": "B)"\}]

    • BetaTextBlock object

      • type: "text"

        default: text

      • citations: array of BetaTextCitation or null

        Citations supporting the text block.

        The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

        • BetaCitationCharLocation object

          • type: "char_location"

            default: char_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_char_index: number

          • file_id: string or null

          • start_char_index: number

            minimum: 0

        • BetaCitationPageLocation object

          • type: "page_location"

            default: page_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_page_number: number

          • file_id: string or null

          • start_page_number: number

            minimum: 1

        • BetaCitationContentBlockLocation object

          • type: "content_block_location"

            default: content_block_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • file_id: string or null

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

        • BetaCitationsWebSearchResultLocation object

          • type: "web_search_result_location"

            default: web_search_result_location

          • cited_text: string

          • encrypted_index: string

          • title: string or null

            maxLength: 512

          • url: string

        • BetaCitationSearchResultLocation object

          • type: "search_result_location"

            default: search_result_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • search_result_index: number

            0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from document_index; server-side web search results are not included in this count.

            minimum: 0

          • source: string

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

          • title: string or null

      • text: string

        minLength: 0

    • BetaThinkingBlock object

      • type: "thinking"

        default: thinking

      • signature: string

        A value used to verify that this thinking block was generated by Claude when it is passed back to the API.

        This is an opaque field and should not be interpreted or parsed. When passing thinking blocks back to the API (required when using tools with extended thinking), pass them back exactly as received, with this field intact.

        See extended thinking for details.

      • thinking: string

        The text of Claude's thinking process for this block.

    • BetaRedactedThinkingBlock object

      • type: "redacted_thinking"

        default: redacted_thinking

      • data: string

        The contents of this redacted thinking block, returned when portions of the model's thinking were safety-redacted. This field is opaque and encrypted, with no readable content.

        Pass redacted_thinking blocks back to the API unchanged when continuing a multi-turn conversation.

        See extended thinking for details.

    • BetaToolUseBlock object

      • type: "tool_use"

        default: tool_use

      • id: string

        pattern: ^[a-zA-Z0-9_-]+$

      • input: map[unknown]

      • name: string

        minLength: 1

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

          • type: "direct"

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

          • type: "code_execution_20250825"

          • tool_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • BetaServerToolCaller20260120 object

          • type: "code_execution_20260120"

          • tool_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • toolset_name: optional string or null

        For a toolset member tool_use, the toolset family.

        maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

    • BetaServerToolUseBlock object

      • type: "server_tool_use"

        default: server_tool_use

      • id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • input: map[unknown]

      • name: "advisor" or "web_search" or "web_fetch" or 5 more

        • "advisor"

        • "web_search"

        • "web_fetch"

        • "code_execution"

        • "bash_code_execution"

        • "text_editor_code_execution"

        • "tool_search_tool_regex"

        • "tool_search_tool_bm25"

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaWebSearchToolResultBlock object

      • type: "web_search_tool_result"

        default: web_search_tool_result

      • content: BetaWebSearchToolResultBlockContent

        • BetaWebSearchToolResultError object

          • type: "web_search_tool_result_error"

            default: web_search_tool_result_error

          • error_code: BetaWebSearchToolResultErrorCode

            • "invalid_tool_input"

            • "unavailable"

            • "max_uses_exceeded"

            • "too_many_requests"

            • "query_too_long"

            • "request_too_large"

        • array of BetaWebSearchResultBlock

          • type: "web_search_result"

            default: web_search_result

          • encrypted_content: string

          • page_age: string or null

          • title: string

          • url: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaWebFetchToolResultBlock object

      • type: "web_fetch_tool_result"

        default: web_fetch_tool_result

      • content: BetaWebFetchToolResultErrorBlock or BetaWebFetchBlock

        • BetaWebFetchToolResultErrorBlock object

          • type: "web_fetch_tool_result_error"

            default: web_fetch_tool_result_error

          • error_code: BetaWebFetchToolResultErrorCode

            • "invalid_tool_input"

            • "url_too_long"

            • "url_not_allowed"

            • "url_not_in_prior_context"

            • "url_not_accessible"

            • "unsupported_content_type"

            • "too_many_requests"

            • "max_uses_exceeded"

            • "unavailable"

            • "content_too_large"

        • BetaWebFetchBlock object

          • type: "web_fetch_result"

            default: web_fetch_result

          • content: BetaDocumentBlock

            • type: "document"

              default: document

            • citations: BetaCitationConfig or null

              Citation configuration for the document

              • enabled: boolean

                default: false

            • source: BetaBase64PDFSource or BetaPlainTextSource

              • BetaBase64PDFSource object

                • type: "base64"

                • data: string

                  format: byte

                • media_type: "application/pdf"

              • BetaPlainTextSource object

                • type: "text"

                • data: string

                • media_type: "text/plain"

            • title: string or null

              The title of the document

          • retrieved_at: string or null

            ISO 8601 timestamp when the content was retrieved

          • url: string

            Fetched content URL

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaAdvisorToolResultBlock object

      • type: "advisor_tool_result"

        default: advisor_tool_result

      • content: BetaAdvisorToolResultError or BetaAdvisorResultBlock or BetaAdvisorRedactedResultBlock

        • BetaAdvisorToolResultError object

          • type: "advisor_tool_result_error"

            default: advisor_tool_result_error

          • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

            • "max_uses_exceeded"

            • "prompt_too_long"

            • "too_many_requests"

            • "overloaded"

            • "unavailable"

            • "execution_time_exceeded"

            • "model_not_found"

        • BetaAdvisorResultBlock object

          • type: "advisor_result"

            default: advisor_result

          • stop_reason: string or null

            The advisor sub-inference's stop reason (same values as the top-level message stop_reason). max_tokens indicates the advisor's output was truncated at the tool's max_tokens value or the advisor model's policy cap.

          • text: string

        • BetaAdvisorRedactedResultBlock object

          • type: "advisor_redacted_result"

            default: advisor_redacted_result

          • encrypted_content: string

            Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

          • stop_reason: string or null

            The advisor sub-inference's stop reason (same values as the top-level message stop_reason).

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaCodeExecutionToolResultBlock object

      • type: "code_execution_tool_result"

        default: code_execution_tool_result

      • content: BetaCodeExecutionToolResultBlockContent

        Code execution result with encrypted stdout for PFC + web_search results.

        • BetaCodeExecutionToolResultError object

          • type: "code_execution_tool_result_error"

            default: code_execution_tool_result_error

          • error_code: BetaCodeExecutionToolResultErrorCode

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

        • BetaCodeExecutionResultBlock object

          • type: "code_execution_result"

            default: code_execution_result

          • content: array of BetaCodeExecutionOutputBlock

            • type: "code_execution_output"

              default: code_execution_output

            • file_id: string

          • return_code: number

          • stderr: string

          • stdout: string

        • BetaEncryptedCodeExecutionResultBlock object

          Code execution result with encrypted stdout for PFC + web_search results.

          • type: "encrypted_code_execution_result"

            default: encrypted_code_execution_result

          • content: array of BetaCodeExecutionOutputBlock

            • type: "code_execution_output"

              default: code_execution_output

            • file_id: string

          • encrypted_stdout: string

          • return_code: number

          • stderr: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaBashCodeExecutionToolResultBlock object

      • type: "bash_code_execution_tool_result"

        default: bash_code_execution_tool_result

      • content: BetaBashCodeExecutionToolResultError or BetaBashCodeExecutionResultBlock

        • BetaBashCodeExecutionToolResultError object

          • type: "bash_code_execution_tool_result_error"

            default: bash_code_execution_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

            • "output_file_too_large"

        • BetaBashCodeExecutionResultBlock object

          • type: "bash_code_execution_result"

            default: bash_code_execution_result

          • content: array of BetaBashCodeExecutionOutputBlock

            • type: "bash_code_execution_output"

              default: bash_code_execution_output

            • file_id: string

          • return_code: number

          • stderr: string

          • stdout: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaTextEditorCodeExecutionToolResultBlock object

      • type: "text_editor_code_execution_tool_result"

        default: text_editor_code_execution_tool_result

      • content: BetaTextEditorCodeExecutionToolResultError or BetaTextEditorCodeExecutionViewResultBlock or BetaTextEditorCodeExecutionCreateResultBlock or BetaTextEditorCodeExecutionStrReplaceResultBlock

        • BetaTextEditorCodeExecutionToolResultError object

          • type: "text_editor_code_execution_tool_result_error"

            default: text_editor_code_execution_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

            • "file_not_found"

          • error_message: string or null

        • BetaTextEditorCodeExecutionViewResultBlock object

          • type: "text_editor_code_execution_view_result"

            default: text_editor_code_execution_view_result

          • content: string

          • file_type: "text" or "image" or "pdf"

            • "text"

            • "image"

            • "pdf"

          • num_lines: number or null

          • start_line: number or null

          • total_lines: number or null

        • BetaTextEditorCodeExecutionCreateResultBlock object

          • type: "text_editor_code_execution_create_result"

            default: text_editor_code_execution_create_result

          • is_file_update: boolean

        • BetaTextEditorCodeExecutionStrReplaceResultBlock object

          • type: "text_editor_code_execution_str_replace_result"

            default: text_editor_code_execution_str_replace_result

          • lines: array of string or null

          • new_lines: number or null

          • new_start: number or null

          • old_lines: number or null

          • old_start: number or null

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaToolSearchToolResultBlock object

      • type: "tool_search_tool_result"

        default: tool_search_tool_result

      • content: BetaToolSearchToolResultError or BetaToolSearchToolSearchResultBlock

        • BetaToolSearchToolResultError object

          • type: "tool_search_tool_result_error"

            default: tool_search_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

          • error_message: string or null

        • BetaToolSearchToolSearchResultBlock object

          • type: "tool_search_tool_search_result"

            default: tool_search_tool_search_result

          • tool_references: array of BetaToolReferenceBlock

            • type: "tool_reference"

              default: tool_reference

            • tool_name: string

              maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaMCPToolUseBlock object

      • type: "mcp_tool_use"

        default: mcp_tool_use

      • id: string

        pattern: ^[a-zA-Z0-9_-]+$

      • input: map[unknown]

      • name: string

        The name of the MCP tool

      • server_name: string

        The name of the MCP server

    • BetaMCPToolResultBlock object

      • type: "mcp_tool_result"

        default: mcp_tool_result

      • content: string or array of BetaTextBlock

        • string

        • BetaMCPToolResultBlockContent = array of BetaTextBlock

          • type: "text"

            default: text

          • citations: array of BetaTextCitation or null

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

          • text: string

            minLength: 0

      • is_error: boolean

        default: false

      • tool_use_id: string

        pattern: ^[a-zA-Z0-9_-]+$

    • BetaContainerUploadBlock object

      Response model for a file uploaded to the container.

      • type: "container_upload"

        default: container_upload

      • file_id: string

    • BetaCompactionBlock object

      A compaction block returned when autocompact is triggered.

      When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

      • type: "compaction"

        default: compaction

      • content: string or null

        Summary of compacted content, or null if compaction failed

      • encrypted_content: string or null

        Opaque metadata from prior compaction, to be round-tripped verbatim

    • BetaFallbackBlock object

      Marks the point in content where one model's output gives way to the next.

      One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

      The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

      • type: "fallback"

        default: fallback

      • from: BetaFallbackInfo

        The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its model echoes the top-level model string the caller sent (alias or canonical); when the declining hop is a fallback model, its model is that model's canonical id.

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

          • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

            The model that will complete your prompt.

            See models for additional details and options.

            • "claude-fable-5-1"

              Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

            • "claude-mythos-5-1"

              Our most capable model for cybersecurity and biology research, available through trusted access programs

            • "claude-sonnet-5"

              High-performance model for coding and agents

            • "claude-fable-5"

              Next generation of intelligence for the hardest knowledge work and coding problems

            • "claude-mythos-5"

              Most capable model for cybersecurity and biology research

            • "claude-opus-5"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-8"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-7"

              Powerful intelligence for long-running agents and coding

            • "claude-mythos-preview"

              New class of intelligence, strongest in coding and cybersecurity

            • "claude-opus-4-6"

              Powerful intelligence for long-running agents and coding

            • "claude-sonnet-4-6"

              Best combination of speed and intelligence

            • "claude-haiku-4-5"

              Fastest model with near-frontier intelligence

            • "claude-haiku-4-5-20251001"

              Fastest model with near-frontier intelligence

            • "claude-opus-4-5"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-5-20251101"

              Powerful intelligence for long-running agents and coding

            • "claude-sonnet-4-5"

              High-performance model for agents and coding

            • "claude-sonnet-4-5-20250929"

              High-performance model for agents and coding

          • string

      • to: BetaFallbackInfo

        The fallback model producing the content that follows this block. Its model is always the canonical id.

      • trigger: BetaFallbackRefusalTrigger

        What caused the from model to hand over at this hop.

        • type: "refusal"

          default: refusal

        • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

          The policy category that triggered a refusal.

          • "cyber"

            The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

          • "bio"

            The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

          • "frontier_llm"

            The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

          • "reasoning_extraction"

            The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

          • "general_harms"

            The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

  • context_management: BetaContextManagementResponse or null

    Context management response.

    Information about context management strategies applied during the request.

    • applied_edits: array of BetaClearToolUses20250919EditResponse or BetaClearThinking20251015EditResponse

      List of context management edits that were applied.

      • BetaClearToolUses20250919EditResponse object

        • type: "clear_tool_uses_20250919"

          The type of context management edit applied.

          default: clear_tool_uses_20250919

        • cleared_input_tokens: number

          Number of input tokens cleared by this edit.

          minimum: 0

        • cleared_tool_uses: number

          Number of tool uses that were cleared.

          minimum: 0

      • BetaClearThinking20251015EditResponse object

        • type: "clear_thinking_20251015"

          The type of context management edit applied.

          default: clear_thinking_20251015

        • cleared_input_tokens: number

          Number of input tokens cleared by this edit.

          minimum: 0

        • cleared_thinking_turns: number

          Number of thinking turns that were cleared.

          minimum: 0

  • diagnostics: BetaDiagnostics or null

    Response envelope for request-level diagnostics. Present (possibly null) whenever the caller supplied diagnostics on the request.

    • cache_miss_reason: BetaCacheMissModelChanged or BetaCacheMissSystemChanged or BetaCacheMissToolsChanged or 3 more or null

      Explains why the prompt cache could not fully reuse the prefix from the request identified by diagnostics.previous_message_id. null means diagnosis is still pending — the response was serialized before the background comparison completed.

      • BetaCacheMissModelChanged object

        • type: "model_changed"

          default: model_changed

        • cache_missed_input_tokens: number

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      • BetaCacheMissSystemChanged object

        • type: "system_changed"

          default: system_changed

        • cache_missed_input_tokens: number

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      • BetaCacheMissToolsChanged object

        • type: "tools_changed"

          default: tools_changed

        • cache_missed_input_tokens: number

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      • BetaCacheMissMessagesChanged object

        • type: "messages_changed"

          default: messages_changed

        • cache_missed_input_tokens: number

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      • BetaCacheMissPreviousMessageNotFound object

        • type: "previous_message_not_found"

          default: previous_message_not_found

      • BetaCacheMissUnavailable object

        • type: "unavailable"

          default: unavailable

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

  • role: "assistant"

    Conversational role of the generated message.

    This will always be "assistant".

    default: assistant

  • stop_details: BetaRefusalStopDetails or null

    Structured information about a refusal.

    • type: "refusal"

      default: refusal

    • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

      The policy category that triggered a refusal.

      • "cyber"

        The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

      • "bio"

        The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

      • "frontier_llm"

        The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

      • "reasoning_extraction"

        The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

      • "general_harms"

        The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

    • explanation: string or null

      Human-readable explanation of the refusal.

      This text is not guaranteed to be stable. null when no explanation is available for the category.

    • fallback_credit_token: string or null

      Opaque code that refunds the cache-miss cost when retrying this refused request on the fallback model. Pass it as fallback_credit_token on the retry request. Expires 5 minutes after the refusal.

      The retry is sent either with the same request body (system, messages, tools, and other render-shaping fields), or with the same body plus one appended assistant message whose content is the partial text (with any trailing whitespace stripped from the final text block) and paired server-tool blocks from this refusal — which also authorizes that appended turn as an assistant-prefill continuation on models that otherwise disallow prefill. A token minted mid-server-tool-loop whose partial content was continuable may only be redeemed the second way — if a same-body retry is rejected with a 400 saying the token must be redeemed by continuing the partial response, retry the second way instead. Either way: same workspace, same platform; a mismatch is a 400. Resending a token for an already-warm prefix is permitted but yields no additional credit.

      null when the refused model isn't eligible for a fallback credit.

    • fallback_has_prefill_claim: boolean or null

      Whether the accompanying fallback_credit_token may be redeemed with the appended-assistant retry form. Only set when fallback_credit_token is present.

      true: retry by resending the same request body plus one appended assistant message whose content is this response's content with any trailing whitespace stripped from the final text block and unpaired tool_use blocks omitted (the same appended-turn shape described on fallback_credit_token), with the token attached. false: retry by resending the original request body unchanged, with the token attached — the appended-assistant form is not available for this refusal (no continuable partial content, or the request uses output_format or a tool_choice that forces tool use). One exception: when the request used output_format or a forced tool_choice and the refusal arrived after server tools (including MCP connector tools) had already executed, the token may not be redeemable by either retry form; if the exact-body retry is then rejected with a 400 saying the token must be redeemed by continuing the partial response, discard the token and retry without it.

      Advisory: if an appended-assistant retry is rejected with a 400 despite true, fall back to resending the original request body with the token.

    • recommended_model: string or null

      The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

  • stop_reason: BetaStopReason or null

    The reason that we stopped.

    This may be one the following values:

    • "end_turn": the model reached a natural stopping point
    • "max_tokens": we exceeded the requested max_tokens or the model's maximum
    • "stop_sequence": one of your provided custom stop_sequences was generated
    • "tool_use": the model invoked one or more tools
    • "pause_turn": we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
    • "refusal": when streaming classifiers intervene to handle potential policy violations
    • "model_context_window_exceeded": we exceeded the model's context window

    In non-streaming mode this value is always non-null. In streaming mode, it is null in the message_start event and non-null otherwise.

    • "end_turn"

    • "max_tokens"

    • "stop_sequence"

    • "tool_use"

    • "pause_turn"

    • "compaction"

    • "refusal"

    • "model_context_window_exceeded"

  • stop_sequence: string or null

    Which custom stop sequence was generated, if any.

    This value will be a non-null string if one of your custom stop sequences was generated.

  • usage: BetaUsage

    Billing and rate-limit usage.

    Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

    Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in usage will not match one-to-one with the exact visible content of an API request or response.

    For example, output_tokens will be non-zero, even for an empty string response from Claude.

    Total input tokens in a request is the summation of input_tokens, cache_creation_input_tokens, and cache_read_input_tokens.

    • cache_creation: BetaCacheCreation or null

      Breakdown of cached tokens by TTL

      • ephemeral_1h_input_tokens: number

        The number of input tokens used to create the 1 hour cache entry.

        default: 0, minimum: 0

      • ephemeral_5m_input_tokens: number

        The number of input tokens used to create the 5 minute cache entry.

        default: 0, minimum: 0

    • cache_creation_input_tokens: number or null

      The number of input tokens used to create the cache entry.

      minimum: 0

    • cache_read_input_tokens: number or null

      The number of input tokens read from the cache.

      minimum: 0

    • fallback_credit: BetaFallbackCreditUsage or null

      Outcome of the fallback_credit_token presented on this request.

      • status: BetaFallbackCreditRedeemed or BetaFallbackCreditNotApplied

        Whether the fallback-credit reprice was applied to this response's billing.

        A union discriminated on type. redeemed: the retry is billed as if the conversation had been on the retry model all along — including when the resulting shift is zero because there was nothing to move. not_applied: no reprice was applied; the arm's reason says why.

        • BetaFallbackCreditRedeemed object

          The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

          • type: "redeemed"

            default: redeemed

        • BetaFallbackCreditNotApplied object

          No reprice was applied; reason says why.

          • type: "not_applied"

            default: not_applied

          • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

            Why the reprice was not applied.

            A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

            • "body_mismatch"

            • "continuation_excluded"

            • "continuation_only"

            • "expired"

            • "invalid_target_model"

            • "not_enabled"

            • "reprice_unavailable"

            • "temporarily_unavailable"

            • "variant_fields_present"

            • "wrong_organization"

            • "wrong_platform"

            • "wrong_workspace"

          • remove_to_redeem: optional array of string or null

            Request fields to remove before retrying, so the retry can redeem this token.

            Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

    • inference_geo: string or null

      The geographic region where inference was performed for this request.

    • input_tokens: number

      The number of input tokens which were used.

      minimum: 0

    • iterations: BetaIterationsUsage or null

      Per-iteration token usage breakdown.

      Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

      • Determine which iterations exceeded long context thresholds (>=200k tokens)
      • Calculate the context window size from the last message entry
      • Understand token accumulation across server-side tool use loops

      A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

      • BetaMessageIterationUsage object

        Token usage for a sampling iteration.

        • type: "message"

          Usage for a sampling iteration

          default: message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaCompactionIterationUsage object

        Token usage for a compaction iteration.

        • type: "compaction"

          Usage for a compaction iteration

          default: compaction

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaAdvisorMessageIterationUsage object

        Token usage for an advisor sub-inference iteration.

        • type: "advisor_message"

          Usage for an advisor sub-inference iteration

          default: advisor_message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaFallbackMessageIterationUsage object

        Token usage for the fallback-model attempt of a server-side fallback request.

        Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

        • type: "fallback_message"

          Usage for the fallback-model attempt that served the response

          default: fallback_message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

    • output_tokens: number

      The number of output tokens which were used.

      minimum: 0

    • output_tokens_details: BetaOutputTokensDetails or null

      Breakdown of output tokens by category.

      output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

      • thinking_tokens: number

        Number of output tokens the model generated as internal reasoning, including the thinking-block delimiter tokens.

        Reflects the raw reasoning the model produced, not the (possibly shorter) summarized thinking text returned in the response body. Computed by re-tokenizing the raw reasoning text, so it may differ from the model's exact generation count by a small number of tokens. Always ≤ output_tokens; output_tokens - thinking_tokens approximates the non-reasoning output.

        default: 0, minimum: 0

    • server_tool_use: BetaServerToolUsage or null

      The number of server tool requests.

      • web_fetch_requests: number

        The number of web fetch tool requests.

        default: 0, minimum: 0

      • web_search_requests: number

        The number of web search tool requests.

        default: 0, minimum: 0

    • service_tier: "standard" or "priority" or "batch" or null

      If the request used the priority, standard, or batch tier.

      • "standard"

      • "priority"

      • "batch"

    • speed: "standard" or "fast" or null

      Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

      • "standard"

      • "fast"

  • input_transformations: optional array of BetaThinkingDroppedInputTransformation or null

    Changes the API made to the request's input before showing it to the model: one entry per change, in request order. Today the only entry type is thinking_dropped — a thinking, redacted_thinking or connector_text block from the request's messages that was removed from the prompt instead of being shown to the model because it failed a binding check. More entry types may be added over time; ignore types you do not recognize.

    Requires anthropic-beta: thinking-binding-controls-2026-08-01. Present on every such response from a model that supports extended thinking, as [] when nothing was changed; without the beta, blocks are removed all the same but nothing is reported. Removed blocks contribute nothing to usage.input_tokens. When streaming, the array is final in message_start; the final message_delta event carries it only when a server-side model fallback happened mid-stream, in which case it holds the serving model's entries and replaces the one in message_start.

    • type: "thinking_dropped"

      Always thinking_dropped for this entry type.

      default: thinking_dropped

    • path: string

      Where the removed block was in your request, as messages.{i}.content.{j}: i indexes the messages array you sent and j that message's content array — the same form error messages use.

    • reason: "model_binding_mismatch" or "prefix_binding_mismatch" or "organization_binding_mismatch" or "end_user_binding_mismatch"

      Which binding check removed the block: model_binding_mismatch — it was created by a model whose reasoning the requested model may not read; prefix_binding_mismatch — the conversation before it differs from the conversation it was created in (the rest of that turn's consecutive thinking blocks are removed with it, each with this reason); organization_binding_mismatch — it was created under a different organization (an Anthropic organization, AWS account or Google Cloud project) and this organization is not one of its additional organizations; end_user_binding_mismatch — it was created for a different end user, or was removed by the consumer-organization binding. A block that would fail several checks reports one reason, in this order of precedence: organization_binding_mismatch, end_user_binding_mismatch, model_binding_mismatch, prefix_binding_mismatch.

      • "model_binding_mismatch"

      • "prefix_binding_mismatch"

      • "organization_binding_mismatch"

      • "end_user_binding_mismatch"

Beta Message Delta Usage

• BetaMessageDeltaUsage object

  • cache_creation_input_tokens: number or null

    The cumulative number of input tokens used to create the cache entry.

    minimum: 0

  • cache_read_input_tokens: number or null

    The cumulative number of input tokens read from the cache.

    minimum: 0

  • fallback_credit: BetaFallbackCreditUsage or null

    Outcome of the fallback_credit_token presented on this request.

    • status: BetaFallbackCreditRedeemed or BetaFallbackCreditNotApplied

      Whether the fallback-credit reprice was applied to this response's billing.

      A union discriminated on type. redeemed: the retry is billed as if the conversation had been on the retry model all along — including when the resulting shift is zero because there was nothing to move. not_applied: no reprice was applied; the arm's reason says why.

      • BetaFallbackCreditRedeemed object

        The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

        • type: "redeemed"

          default: redeemed

      • BetaFallbackCreditNotApplied object

        No reprice was applied; reason says why.

        • type: "not_applied"

          default: not_applied

        • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

          Why the reprice was not applied.

          A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

          • "body_mismatch"

          • "continuation_excluded"

          • "continuation_only"

          • "expired"

          • "invalid_target_model"

          • "not_enabled"

          • "reprice_unavailable"

          • "temporarily_unavailable"

          • "variant_fields_present"

          • "wrong_organization"

          • "wrong_platform"

          • "wrong_workspace"

        • remove_to_redeem: optional array of string or null

          Request fields to remove before retrying, so the retry can redeem this token.

          Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

  • input_tokens: number or null

    The cumulative number of input tokens which were used.

    minimum: 0

  • iterations: BetaIterationsUsage or null

    Per-iteration token usage breakdown.

    Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

    • Determine which iterations exceeded long context thresholds (>=200k tokens)
    • Calculate the context window size from the last message entry
    • Understand token accumulation across server-side tool use loops

    A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

    • BetaMessageIterationUsage object

      Token usage for a sampling iteration.

      • type: "message"

        Usage for a sampling iteration

        default: message

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

        • ephemeral_1h_input_tokens: number

          The number of input tokens used to create the 1 hour cache entry.

          default: 0, minimum: 0

        • ephemeral_5m_input_tokens: number

          The number of input tokens used to create the 5 minute cache entry.

          default: 0, minimum: 0

      • cache_creation_input_tokens: number

        The number of input tokens used to create the cache entry.

        default: 0, minimum: 0

      • cache_read_input_tokens: number

        The number of input tokens read from the cache.

        default: 0, minimum: 0

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

          The model that will complete your prompt.

          See models for additional details and options.

          • "claude-fable-5-1"

            Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

          • "claude-mythos-5-1"

            Our most capable model for cybersecurity and biology research, available through trusted access programs

          • "claude-sonnet-5"

            High-performance model for coding and agents

          • "claude-fable-5"

            Next generation of intelligence for the hardest knowledge work and coding problems

          • "claude-mythos-5"

            Most capable model for cybersecurity and biology research

          • "claude-opus-5"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-8"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-7"

            Powerful intelligence for long-running agents and coding

          • "claude-mythos-preview"

            New class of intelligence, strongest in coding and cybersecurity

          • "claude-opus-4-6"

            Powerful intelligence for long-running agents and coding

          • "claude-sonnet-4-6"

            Best combination of speed and intelligence

          • "claude-haiku-4-5"

            Fastest model with near-frontier intelligence

          • "claude-haiku-4-5-20251001"

            Fastest model with near-frontier intelligence

          • "claude-opus-4-5"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-5-20251101"

            Powerful intelligence for long-running agents and coding

          • "claude-sonnet-4-5"

            High-performance model for agents and coding

          • "claude-sonnet-4-5-20250929"

            High-performance model for agents and coding

        • string

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

    • BetaCompactionIterationUsage object

      Token usage for a compaction iteration.

      • type: "compaction"

        Usage for a compaction iteration

        default: compaction

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

      • cache_creation_input_tokens: number

        The number of input tokens used to create the cache entry.

        default: 0, minimum: 0

      • cache_read_input_tokens: number

        The number of input tokens read from the cache.

        default: 0, minimum: 0

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

    • BetaAdvisorMessageIterationUsage object

      Token usage for an advisor sub-inference iteration.

      • type: "advisor_message"

        Usage for an advisor sub-inference iteration

        default: advisor_message

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

      • cache_creation_input_tokens: number

        The number of input tokens used to create the cache entry.

        default: 0, minimum: 0

      • cache_read_input_tokens: number

        The number of input tokens read from the cache.

        default: 0, minimum: 0

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

    • BetaFallbackMessageIterationUsage object

      Token usage for the fallback-model attempt of a server-side fallback request.

      Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

      • type: "fallback_message"

        Usage for the fallback-model attempt that served the response

        default: fallback_message

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

      • cache_creation_input_tokens: number

        The number of input tokens used to create the cache entry.

        default: 0, minimum: 0

      • cache_read_input_tokens: number

        The number of input tokens read from the cache.

        default: 0, minimum: 0

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

  • output_tokens: number

    The cumulative number of output tokens which were used.

  • output_tokens_details: BetaOutputTokensDetails or null

    Breakdown of output tokens by category.

    output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

    • thinking_tokens: number

      Number of output tokens the model generated as internal reasoning, including the thinking-block delimiter tokens.

      Reflects the raw reasoning the model produced, not the (possibly shorter) summarized thinking text returned in the response body. Computed by re-tokenizing the raw reasoning text, so it may differ from the model's exact generation count by a small number of tokens. Always ≤ output_tokens; output_tokens - thinking_tokens approximates the non-reasoning output.

      default: 0, minimum: 0

  • server_tool_use: BetaServerToolUsage or null

    The number of server tool requests.

    • web_fetch_requests: number

      The number of web fetch tool requests.

      default: 0, minimum: 0

    • web_search_requests: number

      The number of web search tool requests.

      default: 0, minimum: 0

Beta Message Iteration Usage

• BetaMessageIterationUsage object

  Token usage for a sampling iteration.

  • type: "message"

    Usage for a sampling iteration

    default: message

  • cache_creation: BetaCacheCreation or null

    Breakdown of cached tokens by TTL

    • ephemeral_1h_input_tokens: number

      The number of input tokens used to create the 1 hour cache entry.

      default: 0, minimum: 0

    • ephemeral_5m_input_tokens: number

      The number of input tokens used to create the 5 minute cache entry.

      default: 0, minimum: 0

  • cache_creation_input_tokens: number

    The number of input tokens used to create the cache entry.

    default: 0, minimum: 0

  • cache_read_input_tokens: number

    The number of input tokens read from the cache.

    default: 0, minimum: 0

  • input_tokens: number

    The number of input tokens which were used.

    minimum: 0

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1"

        Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

      • "claude-mythos-5-1"

        Our most capable model for cybersecurity and biology research, available through trusted access programs

      • "claude-sonnet-5"

        High-performance model for coding and agents

      • "claude-fable-5"

        Next generation of intelligence for the hardest knowledge work and coding problems

      • "claude-mythos-5"

        Most capable model for cybersecurity and biology research

      • "claude-opus-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-8"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-7"

        Powerful intelligence for long-running agents and coding

      • "claude-mythos-preview"

        New class of intelligence, strongest in coding and cybersecurity

      • "claude-opus-4-6"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-6"

        Best combination of speed and intelligence

      • "claude-haiku-4-5"

        Fastest model with near-frontier intelligence

      • "claude-haiku-4-5-20251001"

        Fastest model with near-frontier intelligence

      • "claude-opus-4-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-5-20251101"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-5"

        High-performance model for agents and coding

      • "claude-sonnet-4-5-20250929"

        High-performance model for agents and coding

    • string

  • output_tokens: number

    The number of output tokens which were used.

    minimum: 0

Beta Message Param

• BetaMessageParam object

  • content: string or array of BetaContentBlockParam

    • string

    • array of BetaContentBlockParam

      • BetaTextBlockParam object

        • type: "text"

        • text: string

          minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

          • type: "ephemeral"

          • ttl: optional "5m" or "1h"

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            • 5m: 5 minutes
            • 1h: 1 hour

            Defaults to 5m. See prompt caching pricing for details.

            • "5m"

            • "1h"

        • citations: optional array of BetaTextCitationParam or null

          • BetaCitationCharLocationParam object

            • type: "char_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_char_index: number

            • start_char_index: number

              minimum: 0

          • BetaCitationPageLocationParam object

            • type: "page_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_page_number: number

            • start_page_number: number

              minimum: 1

          • BetaCitationContentBlockLocationParam object

            • type: "content_block_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

          • BetaCitationWebSearchResultLocationParam object

            • type: "web_search_result_location"

            • cited_text: string

            • encrypted_index: string

            • title: string or null

              maxLength: 512, minLength: 1

            • url: string

              minLength: 1

          • BetaCitationSearchResultLocationParam object

            • type: "search_result_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • search_result_index: number

              0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from document_index; server-side web search results are not included in this count.

              minimum: 0

            • source: string

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

            • title: string or null

      • BetaImageBlockParam object

        • type: "image"

        • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

          • BetaBase64ImageSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

              • "image/jpeg"

              • "image/png"

              • "image/gif"

              • "image/webp"

          • BetaURLImageSource object

            • type: "url"

            • url: string

          • BetaFileImageSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • transformations: optional BetaImageTransformationsParam or null

          Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

          • oversized_image: optional "downsize" or "error"

            What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

            • "downsize"

            • "error"

      • BetaRequestDocumentBlock object

        • type: "document"

        • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

          • BetaBase64PDFSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "application/pdf"

          • BetaPlainTextSource object

            • type: "text"

            • data: string

            • media_type: "text/plain"

          • BetaContentBlockSource object

            • type: "content"

            • content: string or array of BetaContentBlockSourceContent

              • string

              • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

                • BetaTextBlockParam object

                • BetaImageBlockParam object

          • BetaURLPDFSource object

            • type: "url"

            • url: string

          • BetaFileDocumentSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

          • enabled: optional boolean

        • context: optional string or null

          minLength: 1

        • title: optional string or null

          maxLength: 500, minLength: 1

      • BetaSearchResultBlockParam object

        • type: "search_result"

        • content: array of BetaTextBlockParam

          • type: "text"

          • text: string

            minLength: 1

          • cache_control: optional BetaCacheControlEphemeral or null

            Create a cache control breakpoint at this content block.

          • citations: optional array of BetaTextCitationParam or null

        • source: string

        • title: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam

      • BetaThinkingBlockParam object

        • type: "thinking"

        • signature: string

          The signature value of this thinking block, exactly as returned by the API in a previous response. Used to verify that the block was generated by Claude.

          Thinking blocks must be passed back unmodified and in their original order; a modified block results in a 400 invalid_request_error.

        • thinking: string

          The thinking text of this block as returned by the API.

      • BetaRedactedThinkingBlockParam object

        • type: "redacted_thinking"

        • data: string

          The data value of this redacted thinking block, exactly as returned by the API in a previous response. Opaque and encrypted; pass it back unchanged.

      • BetaToolUseBlockParam object

        • type: "tool_use"

        • id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • input: map[unknown]

        • name: string

          maxLength: 200, minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

            • type: "direct"

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

            • type: "code_execution_20250825"

            • tool_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

          • BetaServerToolCaller20260120 object

            • type: "code_execution_20260120"

            • tool_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • toolset_name: optional string or null

          For a toolset member tool_use, the toolset family this member belongs to.

          maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

      • BetaToolResultBlockParam object

        • type: "tool_result"

        • tool_use_id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

          • string

          • array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

            • BetaTextBlockParam object

            • BetaImageBlockParam object

            • BetaSearchResultBlockParam object

            • BetaRequestDocumentBlock object

            • BetaToolReferenceBlockParam object

              Tool reference block that can be included in tool_result content.

              • type: "tool_reference"

              • tool_name: string

                maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

            • BetaBrowserStateBlockParam object

              The caller's browser state after a browser toolset member call — the full inventory of open tabs, which tab is active, and any side effects (tabs opened, download state changes) the call produced.

              At most one per tool_result, only on a non-error result answering a browser toolset member tool_use. The server renders the model-visible text from it; the model never sees the raw fields.

              • type: "browser_state"

              • tabs: array of BetaBrowserStateTabEntry

                All tabs open in the browser after this call — the full inventory, not a delta. May be empty. Whenever non-empty, exactly one entry carries active: true.

                maxItems: 100

                • tab_id: string

                  The caller-assigned identifier for this tab, unique within the inventory.

                  maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • title: string

                  The title of the page the tab is showing. May be empty.

                  maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • url: string

                  The URL of the page the tab is showing. May be empty.

                  maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • active: optional boolean

                  Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

              • state_changes: optional array of BetaBrowserStateChange or null

                Tabs opened and download state changes during this call. "Nothing to report" is expressed by omitting the field, never by an empty list.

                maxItems: 200, minItems: 1

                • BetaBrowserStateChangeTabOpened object

                  A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

                  Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

                  • type: "tab_opened"

                  • tab_id: string

                    The tab_id of the opened tab, present in tabs.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • BetaBrowserStateChangeDownloadStarted object

                  A file download that started during this call.

                  • type: "download_started"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                • BetaBrowserStateChangeDownloadCompleted object

                  A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

                  • type: "download_completed"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • path: optional string or null

                    Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

                    pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

                  • size_bytes: optional number or null

                    The completed download's size.

                    minimum: 0

                • BetaBrowserStateChangeDownloadFailed object

                  A file download that failed — or was cancelled — during this call.

                  • type: "download_failed"

                  • download_id: string

                    The caller-assigned identifier for this download, stable across the state changes reporting it.

                    maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • url: string

                    The final post-redirect URL the download was served from.

                    maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                  • error: optional string or null

                    The failure or cancellation detail, when known.

                    pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

        • is_error: optional boolean

        • toolset_name: optional string or null

          For a toolset member tool_result, the toolset family of the paired tool_use.

          maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

      • BetaServerToolUseBlockParam object

        • type: "server_tool_use"

        • id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • input: map[unknown]

        • name: "advisor" or "web_search" or "web_fetch" or 5 more

          • "advisor"

          • "web_search"

          • "web_fetch"

          • "code_execution"

          • "bash_code_execution"

          • "text_editor_code_execution"

          • "tool_search_tool_regex"

          • "tool_search_tool_bm25"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaWebSearchToolResultBlockParam object

        • type: "web_search_tool_result"

        • content: BetaWebSearchToolResultBlockParamContent

          • ResultBlock = array of BetaWebSearchResultBlockParam

            • type: "web_search_result"

            • encrypted_content: string

            • title: string

            • url: string

            • page_age: optional string or null

          • BetaWebSearchToolRequestError object

            • type: "web_search_tool_result_error"

            • error_code: BetaWebSearchToolResultErrorCode

              • "invalid_tool_input"

              • "unavailable"

              • "max_uses_exceeded"

              • "too_many_requests"

              • "query_too_long"

              • "request_too_large"

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaWebFetchToolResultBlockParam object

        • type: "web_fetch_tool_result"

        • content: BetaWebFetchToolResultErrorBlockParam or BetaWebFetchBlockParam

          • BetaWebFetchToolResultErrorBlockParam object

            • type: "web_fetch_tool_result_error"

            • error_code: BetaWebFetchToolResultErrorCode

              • "invalid_tool_input"

              • "url_too_long"

              • "url_not_allowed"

              • "url_not_in_prior_context"

              • "url_not_accessible"

              • "unsupported_content_type"

              • "too_many_requests"

              • "max_uses_exceeded"

              • "unavailable"

              • "content_too_large"

          • BetaWebFetchBlockParam object

            • type: "web_fetch_result"

            • content: BetaRequestDocumentBlock

            • url: string

              Fetched content URL

            • retrieved_at: optional string or null

              ISO 8601 timestamp when the content was retrieved

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaAdvisorToolResultBlockParam object

        • type: "advisor_tool_result"

        • content: BetaAdvisorToolResultErrorParam or BetaAdvisorResultBlockParam or BetaAdvisorRedactedResultBlockParam

          • BetaAdvisorToolResultErrorParam object

            • type: "advisor_tool_result_error"

            • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

              • "max_uses_exceeded"

              • "prompt_too_long"

              • "too_many_requests"

              • "overloaded"

              • "unavailable"

              • "execution_time_exceeded"

              • "model_not_found"

          • BetaAdvisorResultBlockParam object

            • type: "advisor_result"

            • text: string

            • stop_reason: optional string or null

          • BetaAdvisorRedactedResultBlockParam object

            • type: "advisor_redacted_result"

            • encrypted_content: string

              Opaque blob produced by a prior response; must be round-tripped verbatim.

            • stop_reason: optional string or null

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaCodeExecutionToolResultBlockParam object

        • type: "code_execution_tool_result"

        • content: BetaCodeExecutionToolResultBlockParamContent

          Code execution result with encrypted stdout for PFC + web_search results.

          • BetaCodeExecutionToolResultErrorParam object

            • type: "code_execution_tool_result_error"

            • error_code: BetaCodeExecutionToolResultErrorCode

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

          • BetaCodeExecutionResultBlockParam object

            • type: "code_execution_result"

            • content: array of BetaCodeExecutionOutputBlockParam

              • type: "code_execution_output"

              • file_id: string

            • return_code: number

            • stderr: string

            • stdout: string

          • BetaEncryptedCodeExecutionResultBlockParam object

            Code execution result with encrypted stdout for PFC + web_search results.

            • type: "encrypted_code_execution_result"

            • content: array of BetaCodeExecutionOutputBlockParam

              • type: "code_execution_output"

              • file_id: string

            • encrypted_stdout: string

            • return_code: number

            • stderr: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaBashCodeExecutionToolResultBlockParam object

        • type: "bash_code_execution_tool_result"

        • content: BetaBashCodeExecutionToolResultErrorParam or BetaBashCodeExecutionResultBlockParam

          • BetaBashCodeExecutionToolResultErrorParam object

            • type: "bash_code_execution_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

              • "output_file_too_large"

          • BetaBashCodeExecutionResultBlockParam object

            • type: "bash_code_execution_result"

            • content: array of BetaBashCodeExecutionOutputBlockParam

              • type: "bash_code_execution_output"

              • file_id: string

            • return_code: number

            • stderr: string

            • stdout: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaTextEditorCodeExecutionToolResultBlockParam object

        • type: "text_editor_code_execution_tool_result"

        • content: BetaTextEditorCodeExecutionToolResultErrorParam or BetaTextEditorCodeExecutionViewResultBlockParam or BetaTextEditorCodeExecutionCreateResultBlockParam or BetaTextEditorCodeExecutionStrReplaceResultBlockParam

          • BetaTextEditorCodeExecutionToolResultErrorParam object

            • type: "text_editor_code_execution_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

              • "file_not_found"

            • error_message: optional string or null

          • BetaTextEditorCodeExecutionViewResultBlockParam object

            • type: "text_editor_code_execution_view_result"

            • content: string

            • file_type: "text" or "image" or "pdf"

              • "text"

              • "image"

              • "pdf"

            • num_lines: optional number or null

            • start_line: optional number or null

            • total_lines: optional number or null

          • BetaTextEditorCodeExecutionCreateResultBlockParam object

            • type: "text_editor_code_execution_create_result"

            • is_file_update: boolean

          • BetaTextEditorCodeExecutionStrReplaceResultBlockParam object

            • type: "text_editor_code_execution_str_replace_result"

            • lines: optional array of string or null

            • new_lines: optional number or null

            • new_start: optional number or null

            • old_lines: optional number or null

            • old_start: optional number or null

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaToolSearchToolResultBlockParam object

        • type: "tool_search_tool_result"

        • content: BetaToolSearchToolResultErrorParam or BetaToolSearchToolSearchResultBlockParam

          • BetaToolSearchToolResultErrorParam object

            • type: "tool_search_tool_result_error"

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

            • error_message: optional string or null

          • BetaToolSearchToolSearchResultBlockParam object

            • type: "tool_search_tool_search_result"

            • tool_references: array of BetaToolReferenceBlockParam

              • type: "tool_reference"

              • tool_name: string

                maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaMCPToolUseBlockParam object

        • type: "mcp_tool_use"

        • id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • input: map[unknown]

        • name: string

        • server_name: string

          The name of the MCP server

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaRequestMCPToolResultBlockParam object

        • type: "mcp_tool_result"

        • tool_use_id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or array of BetaTextBlockParam

          • string

          • BetaMCPToolResultBlockParamContent = array of BetaTextBlockParam

            • type: "text"

            • text: string

              minLength: 1

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • citations: optional array of BetaTextCitationParam or null

        • is_error: optional boolean

      • BetaContainerUploadBlockParam object

        A content block that represents a file to be uploaded to the container Files uploaded via this block will be available in the container's input directory.

        • type: "container_upload"

        • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaCompactionBlockParam object

        A compaction block containing summary of previous context.

        Users should round-trip these blocks from responses to subsequent requests to maintain context across compaction boundaries.

        When content is None, the block represents a failed compaction. The server treats these as no-ops. Empty string content is not allowed.

        • type: "compaction"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • content: optional string or null

          Summary of previously compacted content, or null if compaction failed

        • encrypted_content: optional string or null

          Opaque metadata from prior compaction, to be round-tripped verbatim

      • BetaRequestToolAdditionBlock object

        Mid-conversation directive to surface a declared tool.

        tool references a tool (or MCP toolset) by name from the request's tools; it is offered to the model from this point in the conversation onward.

        • type: "tool_addition"

        • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

          Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeToolReference object

            Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

            • type: "tool_reference"

            • name: string

              pattern: ^[a-zA-Z0-9_-]{1,128}$

          • BetaToolChangeMCPToolReference object

            Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

            • type: "mcp_tool_reference"

            • name: string

            • server_name: string

          • BetaToolChangeMCPToolsetReference object

            Reference to every tool in the named MCP server's toolset.

            • type: "mcp_toolset_reference"

            • server_name: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaRequestToolRemovalBlock object

        Mid-conversation directive to withdraw a tool.

        tool references a tool (or MCP toolset) by name from the request's tools; it is no longer offered to the model from this point in the conversation onward.

        • type: "tool_removal"

        • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

          Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeToolReference object

            Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

          • BetaToolChangeMCPToolReference object

            Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

          • BetaToolChangeMCPToolsetReference object

            Reference to every tool in the named MCP server's toolset.

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaFallbackBlockParam object

        A fallback block echoed back from a prior response.

        Accepted in messages[].content and not rendered into the prompt; not validated against the request's fallbacks chain or top-level model.

        Echo the assistant turn back verbatim, including this block in its original position. The block marks the boundary between content produced before and after a fallback hop, and the server relies on that boundary to validate the turn: when thinking runs flank the boundary, omitting the block merges them into one span the server cannot validate (the request is rejected), and moving it into the middle of a single run is likewise rejected; between non-thinking blocks the block's placement has no validation effect.

        • type: "fallback"

        • from: BetaFallbackInfoParam

          Identifies one hop of a fallback transition.

          • model: Model

            The model that will complete your prompt.

            See models for additional details and options.

            • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

              The model that will complete your prompt.

              See models for additional details and options.

              • "claude-fable-5-1"

                Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

              • "claude-mythos-5-1"

                Our most capable model for cybersecurity and biology research, available through trusted access programs

              • "claude-sonnet-5"

                High-performance model for coding and agents

              • "claude-fable-5"

                Next generation of intelligence for the hardest knowledge work and coding problems

              • "claude-mythos-5"

                Most capable model for cybersecurity and biology research

              • "claude-opus-5"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-8"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-7"

                Powerful intelligence for long-running agents and coding

              • "claude-mythos-preview"

                New class of intelligence, strongest in coding and cybersecurity

              • "claude-opus-4-6"

                Powerful intelligence for long-running agents and coding

              • "claude-sonnet-4-6"

                Best combination of speed and intelligence

              • "claude-haiku-4-5"

                Fastest model with near-frontier intelligence

              • "claude-haiku-4-5-20251001"

                Fastest model with near-frontier intelligence

              • "claude-opus-4-5"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-5-20251101"

                Powerful intelligence for long-running agents and coding

              • "claude-sonnet-4-5"

                High-performance model for agents and coding

              • "claude-sonnet-4-5-20250929"

                High-performance model for agents and coding

            • string

        • to: BetaFallbackInfoParam

          Identifies one hop of a fallback transition.

        • trigger: optional unknown

          The response block's trigger, echoed verbatim. Accepted and ignored by the server; any object or null is allowed.

  • role: "user" or "assistant" or "system"

    • "user"

    • "assistant"

    • "system"

  • clear_at: optional "next_user_message" or "never" or null

    How long this system message's text stays in front of the model. "never" (the default) renders it on every request that includes it. "next_user_message" renders it only for the user turn it follows: once a later role: "user" message exists in messages the message stays in the array (send it unchanged) but is no longer shown to the model. Only permitted on role: "system" messages.

    • "next_user_message"

    • "never"

  • output_config: optional BetaSystemMessageOutputConfig or null

    Per-message output configuration on a role:"system" input message.

    Fields here apply per-turn; format remains top-level only. An empty \{\} is accepted on a message that carries content; a message with neither content nor output_config fields is rejected.

    • effort: optional "low" or "medium" or "high" or 2 more or null

      All possible effort levels.

      • "low"

      • "medium"

      • "high"

      • "xhigh"

      • "max"

Beta Message Tokens Count

• BetaMessageTokensCount object

  • context_management: BetaCountTokensContextManagementResponse or null

    Information about context management applied to the message.

    • original_input_tokens: number

      The original token count before context management was applied

  • input_tokens: number

    The total number of tokens across the provided list of messages, system prompt, and tools.

Beta Metadata

• BetaMetadata object

  • user_id: optional string or null

    An external identifier for the user who is associated with the request.

    This should be a uuid, hash value, or other opaque identifier. Anthropic may use this id to help detect abuse. Do not include any identifying information such as name, email address, or phone number.

    maxLength: 512

Beta Output Config

• BetaOutputConfig object

  • effort: optional "low" or "medium" or "high" or 2 more or null

    All possible effort levels.

    • "low"

    • "medium"

    • "high"

    • "xhigh"

    • "max"

  • format: optional BetaJSONOutputFormat or null

    A schema to specify Claude's output format in responses. See structured outputs

    • type: "json_schema"

    • schema: map[unknown]

      The JSON schema of the format

  • task_budget: optional BetaTokenTaskBudget or null

    User-configurable total token budget across contexts.

    • type: "tokens"

      The budget type. Currently only 'tokens' is supported.

    • total: number

      Total token budget across all contexts in the session.

      minimum: 1024

    • remaining: optional number or null

      Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

      minimum: 0

Beta Output Tokens Details

• BetaOutputTokensDetails object

  • thinking_tokens: number

    Number of output tokens the model generated as internal reasoning, including the thinking-block delimiter tokens.

    Reflects the raw reasoning the model produced, not the (possibly shorter) summarized thinking text returned in the response body. Computed by re-tokenizing the raw reasoning text, so it may differ from the model's exact generation count by a small number of tokens. Always ≤ output_tokens; output_tokens - thinking_tokens approximates the non-reasoning output.

    default: 0, minimum: 0

Beta Plain Text Source

• BetaPlainTextSource object

  • type: "text"

  • data: string

  • media_type: "text/plain"

Beta Raw Content Block Delta

• BetaRawContentBlockDelta = BetaTextDelta or BetaInputJSONDelta or BetaCitationsDelta or 3 more

  • BetaTextDelta object

    • type: "text_delta"

      default: text_delta

    • text: string

  • BetaInputJSONDelta object

    • type: "input_json_delta"

      default: input_json_delta

    • partial_json: string

  • BetaCitationsDelta object

    • type: "citations_delta"

      default: citations_delta

    • citation: BetaCitationCharLocation or BetaCitationPageLocation or BetaCitationContentBlockLocation or 2 more

      • BetaCitationCharLocation object

        • type: "char_location"

          default: char_location

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

        • end_char_index: number

        • file_id: string or null

        • start_char_index: number

          minimum: 0

      • BetaCitationPageLocation object

        • type: "page_location"

          default: page_location

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

        • end_page_number: number

        • file_id: string or null

        • start_page_number: number

          minimum: 1

      • BetaCitationContentBlockLocation object

        • type: "content_block_location"

          default: content_block_location

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • document_index: number

          minimum: 0

        • document_title: string or null

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • file_id: string or null

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

      • BetaCitationsWebSearchResultLocation object

        • type: "web_search_result_location"

          default: web_search_result_location

        • cited_text: string

        • encrypted_index: string

        • title: string or null

          maxLength: 512

        • url: string

      • BetaCitationSearchResultLocation object

        • type: "search_result_location"

          default: search_result_location

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • search_result_index: number

          0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from document_index; server-side web search results are not included in this count.

          minimum: 0

        • source: string

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

        • title: string or null

  • BetaThinkingDelta object

    • type: "thinking_delta"

      default: thinking_delta

    • estimated_tokens: number or null

      Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the thinking-token-count-2026-05-13 beta is set; null unless thinking.display resolves to "omitted" and a count is due this frame. Sum the increments across thinking_delta frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; usage.output_tokens remains authoritative.

    • thinking: string

      The incremental thinking text for this content block. Concatenate the thinking values of successive thinking_delta events to assemble the block's full thinking value.

  • BetaSignatureDelta object

    • type: "signature_delta"

      default: signature_delta

    • signature: string

      The signature for this thinking block: an opaque value used to verify that the block was generated by Claude when it is passed back to the API. Delivered in a signature_delta event just before the block's content_block_stop event.

  • BetaCompactionContentBlockDelta object

    • type: "compaction_delta"

      default: compaction_delta

    • content: string or null

    • encrypted_content: string or null

      Opaque metadata from prior compaction, to be round-tripped verbatim

Beta Raw Content Block Delta Event

• BetaRawContentBlockDeltaEvent object

  • type: "content_block_delta"

    default: content_block_delta

  • delta: BetaRawContentBlockDelta

    • BetaTextDelta object

      • type: "text_delta"

        default: text_delta

      • text: string

    • BetaInputJSONDelta object

      • type: "input_json_delta"

        default: input_json_delta

      • partial_json: string

    • BetaCitationsDelta object

      • type: "citations_delta"

        default: citations_delta

      • citation: BetaCitationCharLocation or BetaCitationPageLocation or BetaCitationContentBlockLocation or 2 more

        • BetaCitationCharLocation object

          • type: "char_location"

            default: char_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_char_index: number

          • file_id: string or null

          • start_char_index: number

            minimum: 0

        • BetaCitationPageLocation object

          • type: "page_location"

            default: page_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_page_number: number

          • file_id: string or null

          • start_page_number: number

            minimum: 1

        • BetaCitationContentBlockLocation object

          • type: "content_block_location"

            default: content_block_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • file_id: string or null

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

        • BetaCitationsWebSearchResultLocation object

          • type: "web_search_result_location"

            default: web_search_result_location

          • cited_text: string

          • encrypted_index: string

          • title: string or null

            maxLength: 512

          • url: string

        • BetaCitationSearchResultLocation object

          • type: "search_result_location"

            default: search_result_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • search_result_index: number

            0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from document_index; server-side web search results are not included in this count.

            minimum: 0

          • source: string

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

          • title: string or null

    • BetaThinkingDelta object

      • type: "thinking_delta"

        default: thinking_delta

      • estimated_tokens: number or null

        Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the thinking-token-count-2026-05-13 beta is set; null unless thinking.display resolves to "omitted" and a count is due this frame. Sum the increments across thinking_delta frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; usage.output_tokens remains authoritative.

      • thinking: string

        The incremental thinking text for this content block. Concatenate the thinking values of successive thinking_delta events to assemble the block's full thinking value.

    • BetaSignatureDelta object

      • type: "signature_delta"

        default: signature_delta

      • signature: string

        The signature for this thinking block: an opaque value used to verify that the block was generated by Claude when it is passed back to the API. Delivered in a signature_delta event just before the block's content_block_stop event.

    • BetaCompactionContentBlockDelta object

      • type: "compaction_delta"

        default: compaction_delta

      • content: string or null

      • encrypted_content: string or null

        Opaque metadata from prior compaction, to be round-tripped verbatim

  • index: number

Beta Raw Content Block Start Event

• BetaRawContentBlockStartEvent object

  • type: "content_block_start"

    default: content_block_start

  • content_block: BetaTextBlock or BetaThinkingBlock or BetaRedactedThinkingBlock or 14 more

    Response model for a file uploaded to the container.

    • BetaTextBlock object

      • type: "text"

        default: text

      • citations: array of BetaTextCitation or null

        Citations supporting the text block.

        The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

        • BetaCitationCharLocation object

          • type: "char_location"

            default: char_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_char_index: number

          • file_id: string or null

          • start_char_index: number

            minimum: 0

        • BetaCitationPageLocation object

          • type: "page_location"

            default: page_location

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_page_number: number

          • file_id: string or null

          • start_page_number: number

            minimum: 1

        • BetaCitationContentBlockLocation object

          • type: "content_block_location"

            default: content_block_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • document_index: number

            minimum: 0

          • document_title: string or null

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • file_id: string or null

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

        • BetaCitationsWebSearchResultLocation object

          • type: "web_search_result_location"

            default: web_search_result_location

          • cited_text: string

          • encrypted_index: string

          • title: string or null

            maxLength: 512

          • url: string

        • BetaCitationSearchResultLocation object

          • type: "search_result_location"

            default: search_result_location

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • search_result_index: number

            0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from document_index; server-side web search results are not included in this count.

            minimum: 0

          • source: string

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

          • title: string or null

      • text: string

        minLength: 0

    • BetaThinkingBlock object

      • type: "thinking"

        default: thinking

      • signature: string

        A value used to verify that this thinking block was generated by Claude when it is passed back to the API.

        This is an opaque field and should not be interpreted or parsed. When passing thinking blocks back to the API (required when using tools with extended thinking), pass them back exactly as received, with this field intact.

        See extended thinking for details.

      • thinking: string

        The text of Claude's thinking process for this block.

    • BetaRedactedThinkingBlock object

      • type: "redacted_thinking"

        default: redacted_thinking

      • data: string

        The contents of this redacted thinking block, returned when portions of the model's thinking were safety-redacted. This field is opaque and encrypted, with no readable content.

        Pass redacted_thinking blocks back to the API unchanged when continuing a multi-turn conversation.

        See extended thinking for details.

    • BetaToolUseBlock object

      • type: "tool_use"

        default: tool_use

      • id: string

        pattern: ^[a-zA-Z0-9_-]+$

      • input: map[unknown]

      • name: string

        minLength: 1

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

          • type: "direct"

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

          • type: "code_execution_20250825"

          • tool_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • BetaServerToolCaller20260120 object

          • type: "code_execution_20260120"

          • tool_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • toolset_name: optional string or null

        For a toolset member tool_use, the toolset family.

        maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

    • BetaServerToolUseBlock object

      • type: "server_tool_use"

        default: server_tool_use

      • id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • input: map[unknown]

      • name: "advisor" or "web_search" or "web_fetch" or 5 more

        • "advisor"

        • "web_search"

        • "web_fetch"

        • "code_execution"

        • "bash_code_execution"

        • "text_editor_code_execution"

        • "tool_search_tool_regex"

        • "tool_search_tool_bm25"

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaWebSearchToolResultBlock object

      • type: "web_search_tool_result"

        default: web_search_tool_result

      • content: BetaWebSearchToolResultBlockContent

        • BetaWebSearchToolResultError object

          • type: "web_search_tool_result_error"

            default: web_search_tool_result_error

          • error_code: BetaWebSearchToolResultErrorCode

            • "invalid_tool_input"

            • "unavailable"

            • "max_uses_exceeded"

            • "too_many_requests"

            • "query_too_long"

            • "request_too_large"

        • array of BetaWebSearchResultBlock

          • type: "web_search_result"

            default: web_search_result

          • encrypted_content: string

          • page_age: string or null

          • title: string

          • url: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaWebFetchToolResultBlock object

      • type: "web_fetch_tool_result"

        default: web_fetch_tool_result

      • content: BetaWebFetchToolResultErrorBlock or BetaWebFetchBlock

        • BetaWebFetchToolResultErrorBlock object

          • type: "web_fetch_tool_result_error"

            default: web_fetch_tool_result_error

          • error_code: BetaWebFetchToolResultErrorCode

            • "invalid_tool_input"

            • "url_too_long"

            • "url_not_allowed"

            • "url_not_in_prior_context"

            • "url_not_accessible"

            • "unsupported_content_type"

            • "too_many_requests"

            • "max_uses_exceeded"

            • "unavailable"

            • "content_too_large"

        • BetaWebFetchBlock object

          • type: "web_fetch_result"

            default: web_fetch_result

          • content: BetaDocumentBlock

            • type: "document"

              default: document

            • citations: BetaCitationConfig or null

              Citation configuration for the document

              • enabled: boolean

                default: false

            • source: BetaBase64PDFSource or BetaPlainTextSource

              • BetaBase64PDFSource object

                • type: "base64"

                • data: string

                  format: byte

                • media_type: "application/pdf"

              • BetaPlainTextSource object

                • type: "text"

                • data: string

                • media_type: "text/plain"

            • title: string or null

              The title of the document

          • retrieved_at: string or null

            ISO 8601 timestamp when the content was retrieved

          • url: string

            Fetched content URL

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

        Tool invocation directly from the model.

        • BetaDirectCaller object

          Tool invocation directly from the model.

        • BetaServerToolCaller object

          Tool invocation generated by a server-side tool.

        • BetaServerToolCaller20260120 object

    • BetaAdvisorToolResultBlock object

      • type: "advisor_tool_result"

        default: advisor_tool_result

      • content: BetaAdvisorToolResultError or BetaAdvisorResultBlock or BetaAdvisorRedactedResultBlock

        • BetaAdvisorToolResultError object

          • type: "advisor_tool_result_error"

            default: advisor_tool_result_error

          • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

            • "max_uses_exceeded"

            • "prompt_too_long"

            • "too_many_requests"

            • "overloaded"

            • "unavailable"

            • "execution_time_exceeded"

            • "model_not_found"

        • BetaAdvisorResultBlock object

          • type: "advisor_result"

            default: advisor_result

          • stop_reason: string or null

            The advisor sub-inference's stop reason (same values as the top-level message stop_reason). max_tokens indicates the advisor's output was truncated at the tool's max_tokens value or the advisor model's policy cap.

          • text: string

        • BetaAdvisorRedactedResultBlock object

          • type: "advisor_redacted_result"

            default: advisor_redacted_result

          • encrypted_content: string

            Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

          • stop_reason: string or null

            The advisor sub-inference's stop reason (same values as the top-level message stop_reason).

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaCodeExecutionToolResultBlock object

      • type: "code_execution_tool_result"

        default: code_execution_tool_result

      • content: BetaCodeExecutionToolResultBlockContent

        Code execution result with encrypted stdout for PFC + web_search results.

        • BetaCodeExecutionToolResultError object

          • type: "code_execution_tool_result_error"

            default: code_execution_tool_result_error

          • error_code: BetaCodeExecutionToolResultErrorCode

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

        • BetaCodeExecutionResultBlock object

          • type: "code_execution_result"

            default: code_execution_result

          • content: array of BetaCodeExecutionOutputBlock

            • type: "code_execution_output"

              default: code_execution_output

            • file_id: string

          • return_code: number

          • stderr: string

          • stdout: string

        • BetaEncryptedCodeExecutionResultBlock object

          Code execution result with encrypted stdout for PFC + web_search results.

          • type: "encrypted_code_execution_result"

            default: encrypted_code_execution_result

          • content: array of BetaCodeExecutionOutputBlock

            • type: "code_execution_output"

              default: code_execution_output

            • file_id: string

          • encrypted_stdout: string

          • return_code: number

          • stderr: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaBashCodeExecutionToolResultBlock object

      • type: "bash_code_execution_tool_result"

        default: bash_code_execution_tool_result

      • content: BetaBashCodeExecutionToolResultError or BetaBashCodeExecutionResultBlock

        • BetaBashCodeExecutionToolResultError object

          • type: "bash_code_execution_tool_result_error"

            default: bash_code_execution_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

            • "output_file_too_large"

        • BetaBashCodeExecutionResultBlock object

          • type: "bash_code_execution_result"

            default: bash_code_execution_result

          • content: array of BetaBashCodeExecutionOutputBlock

            • type: "bash_code_execution_output"

              default: bash_code_execution_output

            • file_id: string

          • return_code: number

          • stderr: string

          • stdout: string

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaTextEditorCodeExecutionToolResultBlock object

      • type: "text_editor_code_execution_tool_result"

        default: text_editor_code_execution_tool_result

      • content: BetaTextEditorCodeExecutionToolResultError or BetaTextEditorCodeExecutionViewResultBlock or BetaTextEditorCodeExecutionCreateResultBlock or BetaTextEditorCodeExecutionStrReplaceResultBlock

        • BetaTextEditorCodeExecutionToolResultError object

          • type: "text_editor_code_execution_tool_result_error"

            default: text_editor_code_execution_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

            • "file_not_found"

          • error_message: string or null

        • BetaTextEditorCodeExecutionViewResultBlock object

          • type: "text_editor_code_execution_view_result"

            default: text_editor_code_execution_view_result

          • content: string

          • file_type: "text" or "image" or "pdf"

            • "text"

            • "image"

            • "pdf"

          • num_lines: number or null

          • start_line: number or null

          • total_lines: number or null

        • BetaTextEditorCodeExecutionCreateResultBlock object

          • type: "text_editor_code_execution_create_result"

            default: text_editor_code_execution_create_result

          • is_file_update: boolean

        • BetaTextEditorCodeExecutionStrReplaceResultBlock object

          • type: "text_editor_code_execution_str_replace_result"

            default: text_editor_code_execution_str_replace_result

          • lines: array of string or null

          • new_lines: number or null

          • new_start: number or null

          • old_lines: number or null

          • old_start: number or null

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaToolSearchToolResultBlock object

      • type: "tool_search_tool_result"

        default: tool_search_tool_result

      • content: BetaToolSearchToolResultError or BetaToolSearchToolSearchResultBlock

        • BetaToolSearchToolResultError object

          • type: "tool_search_tool_result_error"

            default: tool_search_tool_result_error

          • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

            • "invalid_tool_input"

            • "unavailable"

            • "too_many_requests"

            • "execution_time_exceeded"

          • error_message: string or null

        • BetaToolSearchToolSearchResultBlock object

          • type: "tool_search_tool_search_result"

            default: tool_search_tool_search_result

          • tool_references: array of BetaToolReferenceBlock

            • type: "tool_reference"

              default: tool_reference

            • tool_name: string

              maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

      • tool_use_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaMCPToolUseBlock object

      • type: "mcp_tool_use"

        default: mcp_tool_use

      • id: string

        pattern: ^[a-zA-Z0-9_-]+$

      • input: map[unknown]

      • name: string

        The name of the MCP tool

      • server_name: string

        The name of the MCP server

    • BetaMCPToolResultBlock object

      • type: "mcp_tool_result"

        default: mcp_tool_result

      • content: string or array of BetaTextBlock

        • string

        • BetaMCPToolResultBlockContent = array of BetaTextBlock

          • type: "text"

            default: text

          • citations: array of BetaTextCitation or null

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

          • text: string

            minLength: 0

      • is_error: boolean

        default: false

      • tool_use_id: string

        pattern: ^[a-zA-Z0-9_-]+$

    • BetaContainerUploadBlock object

      Response model for a file uploaded to the container.

      • type: "container_upload"

        default: container_upload

      • file_id: string

    • BetaCompactionBlock object

      A compaction block returned when autocompact is triggered.

      When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

      • type: "compaction"

        default: compaction

      • content: string or null

        Summary of compacted content, or null if compaction failed

      • encrypted_content: string or null

        Opaque metadata from prior compaction, to be round-tripped verbatim

    • BetaFallbackBlock object

      Marks the point in content where one model's output gives way to the next.

      One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

      The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

      • type: "fallback"

        default: fallback

      • from: BetaFallbackInfo

        The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its model echoes the top-level model string the caller sent (alias or canonical); when the declining hop is a fallback model, its model is that model's canonical id.

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

          • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

            The model that will complete your prompt.

            See models for additional details and options.

            • "claude-fable-5-1"

              Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

            • "claude-mythos-5-1"

              Our most capable model for cybersecurity and biology research, available through trusted access programs

            • "claude-sonnet-5"

              High-performance model for coding and agents

            • "claude-fable-5"

              Next generation of intelligence for the hardest knowledge work and coding problems

            • "claude-mythos-5"

              Most capable model for cybersecurity and biology research

            • "claude-opus-5"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-8"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-7"

              Powerful intelligence for long-running agents and coding

            • "claude-mythos-preview"

              New class of intelligence, strongest in coding and cybersecurity

            • "claude-opus-4-6"

              Powerful intelligence for long-running agents and coding

            • "claude-sonnet-4-6"

              Best combination of speed and intelligence

            • "claude-haiku-4-5"

              Fastest model with near-frontier intelligence

            • "claude-haiku-4-5-20251001"

              Fastest model with near-frontier intelligence

            • "claude-opus-4-5"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-5-20251101"

              Powerful intelligence for long-running agents and coding

            • "claude-sonnet-4-5"

              High-performance model for agents and coding

            • "claude-sonnet-4-5-20250929"

              High-performance model for agents and coding

          • string

      • to: BetaFallbackInfo

        The fallback model producing the content that follows this block. Its model is always the canonical id.

      • trigger: BetaFallbackRefusalTrigger

        What caused the from model to hand over at this hop.

        • type: "refusal"

          default: refusal

        • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

          The policy category that triggered a refusal.

          • "cyber"

            The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

          • "bio"

            The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

          • "frontier_llm"

            The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

          • "reasoning_extraction"

            The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

          • "general_harms"

            The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

  • index: number

Beta Raw Content Block Stop Event

• BetaRawContentBlockStopEvent object

  • type: "content_block_stop"

    default: content_block_stop

  • index: number

Beta Raw Message Delta Event

• BetaRawMessageDeltaEvent object

  • type: "message_delta"

    default: message_delta

  • context_management: BetaContextManagementResponse or null

    Information about context management strategies applied during the request

    • applied_edits: array of BetaClearToolUses20250919EditResponse or BetaClearThinking20251015EditResponse

      List of context management edits that were applied.

      • BetaClearToolUses20250919EditResponse object

        • type: "clear_tool_uses_20250919"

          The type of context management edit applied.

          default: clear_tool_uses_20250919

        • cleared_input_tokens: number

          Number of input tokens cleared by this edit.

          minimum: 0

        • cleared_tool_uses: number

          Number of tool uses that were cleared.

          minimum: 0

      • BetaClearThinking20251015EditResponse object

        • type: "clear_thinking_20251015"

          The type of context management edit applied.

          default: clear_thinking_20251015

        • cleared_input_tokens: number

          Number of input tokens cleared by this edit.

          minimum: 0

        • cleared_thinking_turns: number

          Number of thinking turns that were cleared.

          minimum: 0

  • delta: object

    • container: BetaContainer or null

      Information about the container used in the request (for the code execution tool)

      • id: string

        Identifier for the container used in this request

      • expires_at: string

        The time at which the container will expire.

        format: date-time

      • skills: array of BetaContainerSkill or null

        Skills loaded in the container

        • type: "anthropic" or "custom"

          Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

          • "anthropic"

          • "custom"

        • skill_id: string

          Skill ID

          maxLength: 64, minLength: 1

        • version: string

          The resolved version: a skill version ID for custom skills.

          maxLength: 64, minLength: 1

    • stop_details: BetaRefusalStopDetails or null

      Structured information about a refusal.

      • type: "refusal"

        default: refusal

      • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

        The policy category that triggered a refusal.

        • "cyber"

          The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

        • "bio"

          The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

        • "frontier_llm"

          The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

        • "reasoning_extraction"

          The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

        • "general_harms"

          The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

      • explanation: string or null

        Human-readable explanation of the refusal.

        This text is not guaranteed to be stable. null when no explanation is available for the category.

      • fallback_credit_token: string or null

        Opaque code that refunds the cache-miss cost when retrying this refused request on the fallback model. Pass it as fallback_credit_token on the retry request. Expires 5 minutes after the refusal.

        The retry is sent either with the same request body (system, messages, tools, and other render-shaping fields), or with the same body plus one appended assistant message whose content is the partial text (with any trailing whitespace stripped from the final text block) and paired server-tool blocks from this refusal — which also authorizes that appended turn as an assistant-prefill continuation on models that otherwise disallow prefill. A token minted mid-server-tool-loop whose partial content was continuable may only be redeemed the second way — if a same-body retry is rejected with a 400 saying the token must be redeemed by continuing the partial response, retry the second way instead. Either way: same workspace, same platform; a mismatch is a 400. Resending a token for an already-warm prefix is permitted but yields no additional credit.

        null when the refused model isn't eligible for a fallback credit.

      • fallback_has_prefill_claim: boolean or null

        Whether the accompanying fallback_credit_token may be redeemed with the appended-assistant retry form. Only set when fallback_credit_token is present.

        true: retry by resending the same request body plus one appended assistant message whose content is this response's content with any trailing whitespace stripped from the final text block and unpaired tool_use blocks omitted (the same appended-turn shape described on fallback_credit_token), with the token attached. false: retry by resending the original request body unchanged, with the token attached — the appended-assistant form is not available for this refusal (no continuable partial content, or the request uses output_format or a tool_choice that forces tool use). One exception: when the request used output_format or a forced tool_choice and the refusal arrived after server tools (including MCP connector tools) had already executed, the token may not be redeemable by either retry form; if the exact-body retry is then rejected with a 400 saying the token must be redeemed by continuing the partial response, discard the token and retry without it.

        Advisory: if an appended-assistant retry is rejected with a 400 despite true, fall back to resending the original request body with the token.

      • recommended_model: string or null

        The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

    • stop_reason: BetaStopReason or null

      • "end_turn"

      • "max_tokens"

      • "stop_sequence"

      • "tool_use"

      • "pause_turn"

      • "compaction"

      • "refusal"

      • "model_context_window_exceeded"

    • stop_sequence: string or null

  • usage: BetaMessageDeltaUsage

    Billing and rate-limit usage.

    Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

    Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in usage will not match one-to-one with the exact visible content of an API request or response.

    For example, output_tokens will be non-zero, even for an empty string response from Claude.

    Total input tokens in a request is the summation of input_tokens, cache_creation_input_tokens, and cache_read_input_tokens.

    • cache_creation_input_tokens: number or null

      The cumulative number of input tokens used to create the cache entry.

      minimum: 0

    • cache_read_input_tokens: number or null

      The cumulative number of input tokens read from the cache.

      minimum: 0

    • fallback_credit: BetaFallbackCreditUsage or null

      Outcome of the fallback_credit_token presented on this request.

      • status: BetaFallbackCreditRedeemed or BetaFallbackCreditNotApplied

        Whether the fallback-credit reprice was applied to this response's billing.

        A union discriminated on type. redeemed: the retry is billed as if the conversation had been on the retry model all along — including when the resulting shift is zero because there was nothing to move. not_applied: no reprice was applied; the arm's reason says why.

        • BetaFallbackCreditRedeemed object

          The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

          • type: "redeemed"

            default: redeemed

        • BetaFallbackCreditNotApplied object

          No reprice was applied; reason says why.

          • type: "not_applied"

            default: not_applied

          • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

            Why the reprice was not applied.

            A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

            • "body_mismatch"

            • "continuation_excluded"

            • "continuation_only"

            • "expired"

            • "invalid_target_model"

            • "not_enabled"

            • "reprice_unavailable"

            • "temporarily_unavailable"

            • "variant_fields_present"

            • "wrong_organization"

            • "wrong_platform"

            • "wrong_workspace"

          • remove_to_redeem: optional array of string or null

            Request fields to remove before retrying, so the retry can redeem this token.

            Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

    • input_tokens: number or null

      The cumulative number of input tokens which were used.

      minimum: 0

    • iterations: BetaIterationsUsage or null

      Per-iteration token usage breakdown.

      Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

      • Determine which iterations exceeded long context thresholds (>=200k tokens)
      • Calculate the context window size from the last message entry
      • Understand token accumulation across server-side tool use loops

      A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

      • BetaMessageIterationUsage object

        Token usage for a sampling iteration.

        • type: "message"

          Usage for a sampling iteration

          default: message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

          • ephemeral_1h_input_tokens: number

            The number of input tokens used to create the 1 hour cache entry.

            default: 0, minimum: 0

          • ephemeral_5m_input_tokens: number

            The number of input tokens used to create the 5 minute cache entry.

            default: 0, minimum: 0

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

          • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

            The model that will complete your prompt.

            See models for additional details and options.

            • "claude-fable-5-1"

              Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

            • "claude-mythos-5-1"

              Our most capable model for cybersecurity and biology research, available through trusted access programs

            • "claude-sonnet-5"

              High-performance model for coding and agents

            • "claude-fable-5"

              Next generation of intelligence for the hardest knowledge work and coding problems

            • "claude-mythos-5"

              Most capable model for cybersecurity and biology research

            • "claude-opus-5"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-8"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-7"

              Powerful intelligence for long-running agents and coding

            • "claude-mythos-preview"

              New class of intelligence, strongest in coding and cybersecurity

            • "claude-opus-4-6"

              Powerful intelligence for long-running agents and coding

            • "claude-sonnet-4-6"

              Best combination of speed and intelligence

            • "claude-haiku-4-5"

              Fastest model with near-frontier intelligence

            • "claude-haiku-4-5-20251001"

              Fastest model with near-frontier intelligence

            • "claude-opus-4-5"

              Powerful intelligence for long-running agents and coding

            • "claude-opus-4-5-20251101"

              Powerful intelligence for long-running agents and coding

            • "claude-sonnet-4-5"

              High-performance model for agents and coding

            • "claude-sonnet-4-5-20250929"

              High-performance model for agents and coding

          • string

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaCompactionIterationUsage object

        Token usage for a compaction iteration.

        • type: "compaction"

          Usage for a compaction iteration

          default: compaction

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaAdvisorMessageIterationUsage object

        Token usage for an advisor sub-inference iteration.

        • type: "advisor_message"

          Usage for an advisor sub-inference iteration

          default: advisor_message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

      • BetaFallbackMessageIterationUsage object

        Token usage for the fallback-model attempt of a server-side fallback request.

        Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

        • type: "fallback_message"

          Usage for the fallback-model attempt that served the response

          default: fallback_message

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

        • cache_creation_input_tokens: number

          The number of input tokens used to create the cache entry.

          default: 0, minimum: 0

        • cache_read_input_tokens: number

          The number of input tokens read from the cache.

          default: 0, minimum: 0

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

    • output_tokens: number

      The cumulative number of output tokens which were used.

    • output_tokens_details: BetaOutputTokensDetails or null

      Breakdown of output tokens by category.

      output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

      • thinking_tokens: number

        Number of output tokens the model generated as internal reasoning, including the thinking-block delimiter tokens.

        Reflects the raw reasoning the model produced, not the (possibly shorter) summarized thinking text returned in the response body. Computed by re-tokenizing the raw reasoning text, so it may differ from the model's exact generation count by a small number of tokens. Always ≤ output_tokens; output_tokens - thinking_tokens approximates the non-reasoning output.

        default: 0, minimum: 0

    • server_tool_use: BetaServerToolUsage or null

      The number of server tool requests.

      • web_fetch_requests: number

        The number of web fetch tool requests.

        default: 0, minimum: 0

      • web_search_requests: number

        The number of web search tool requests.

        default: 0, minimum: 0

  • input_transformations: optional array of BetaThinkingDroppedInputTransformation or null

    Changes the API made to the request's input before showing it to the model: one entry per change, in request order. Today the only entry type is thinking_dropped — a thinking, redacted_thinking or connector_text block from the request's messages that was removed from the prompt instead of being shown to the model because it failed a binding check. More entry types may be added over time; ignore types you do not recognize.

    Requires anthropic-beta: thinking-binding-controls-2026-08-01. Present on every such response from a model that supports extended thinking, as [] when nothing was changed; without the beta, blocks are removed all the same but nothing is reported. Removed blocks contribute nothing to usage.input_tokens. When streaming, the array is final in message_start; the final message_delta event carries it only when a server-side model fallback happened mid-stream, in which case it holds the serving model's entries and replaces the one in message_start.

    • type: "thinking_dropped"

      Always thinking_dropped for this entry type.

      default: thinking_dropped

    • path: string

      Where the removed block was in your request, as messages.{i}.content.{j}: i indexes the messages array you sent and j that message's content array — the same form error messages use.

    • reason: "model_binding_mismatch" or "prefix_binding_mismatch" or "organization_binding_mismatch" or "end_user_binding_mismatch"

      Which binding check removed the block: model_binding_mismatch — it was created by a model whose reasoning the requested model may not read; prefix_binding_mismatch — the conversation before it differs from the conversation it was created in (the rest of that turn's consecutive thinking blocks are removed with it, each with this reason); organization_binding_mismatch — it was created under a different organization (an Anthropic organization, AWS account or Google Cloud project) and this organization is not one of its additional organizations; end_user_binding_mismatch — it was created for a different end user, or was removed by the consumer-organization binding. A block that would fail several checks reports one reason, in this order of precedence: organization_binding_mismatch, end_user_binding_mismatch, model_binding_mismatch, prefix_binding_mismatch.

      • "model_binding_mismatch"

      • "prefix_binding_mismatch"

      • "organization_binding_mismatch"

      • "end_user_binding_mismatch"

Beta Raw Message Start Event

• BetaRawMessageStartEvent object

  • type: "message_start"

    default: message_start

  • message: BetaMessage

    • type: "message"

      Object type.

      For Messages, this is always "message".

      default: message

    • id: string

      Unique object identifier.

      The format and length of IDs may change over time.

    • container: BetaContainer or null

      Information about the container used in the request (for the code execution tool)

      • id: string

        Identifier for the container used in this request

      • expires_at: string

        The time at which the container will expire.

        format: date-time

      • skills: array of BetaContainerSkill or null

        Skills loaded in the container

        • type: "anthropic" or "custom"

          Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

          • "anthropic"

          • "custom"

        • skill_id: string

          Skill ID

          maxLength: 64, minLength: 1

        • version: string

          The resolved version: a skill version ID for custom skills.

          maxLength: 64, minLength: 1

    • content: array of BetaContentBlock

      Content generated by the model.

      This is an array of content blocks, each of which has a type that determines its shape.

      Example:

      [{"type": "text", "text": "Hi, I'm Claude."}]

      If the request input messages ended with an assistant turn, then the response content will continue directly from that last turn. You can use this to constrain the model's output.

      For example, if the input messages were:

      [
        {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
        {"role": "assistant", "content": "The best answer is ("}
      ]

      Then the response content might be:

      [{"type": "text", "text": "B)"}]

      • BetaTextBlock object

        • type: "text"

          default: text

        • citations: array of BetaTextCitation or null

          Citations supporting the text block.

          The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

          • BetaCitationCharLocation object

            • type: "char_location"

              default: char_location

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

            • end_char_index: number

            • file_id: string or null

            • start_char_index: number

              minimum: 0

          • BetaCitationPageLocation object

            • type: "page_location"

              default: page_location

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

            • end_page_number: number

            • file_id: string or null

            • start_page_number: number

              minimum: 1

          • BetaCitationContentBlockLocation object

            • type: "content_block_location"

              default: content_block_location

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • document_index: number

              minimum: 0

            • document_title: string or null

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • file_id: string or null

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

          • BetaCitationsWebSearchResultLocation object

            • type: "web_search_result_location"

              default: web_search_result_location

            • cited_text: string

            • encrypted_index: string

            • title: string or null

              maxLength: 512

            • url: string

          • BetaCitationSearchResultLocation object

            • type: "search_result_location"

              default: search_result_location

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • search_result_index: number

              0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from document_index; server-side web search results are not included in this count.

              minimum: 0

            • source: string

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

            • title: string or null

        • text: string

          minLength: 0

      • BetaThinkingBlock object

        • type: "thinking"

          default: thinking

        • signature: string

          A value used to verify that this thinking block was generated by Claude when it is passed back to the API.

          This is an opaque field and should not be interpreted or parsed. When passing thinking blocks back to the API (required when using tools with extended thinking), pass them back exactly as received, with this field intact.

          See extended thinking for details.

        • thinking: string

          The text of Claude's thinking process for this block.

      • BetaRedactedThinkingBlock object

        • type: "redacted_thinking"

          default: redacted_thinking

        • data: string

          The contents of this redacted thinking block, returned when portions of the model's thinking were safety-redacted. This field is opaque and encrypted, with no readable content.

          Pass redacted_thinking blocks back to the API unchanged when continuing a multi-turn conversation.

          See extended thinking for details.

      • BetaToolUseBlock object

        • type: "tool_use"

          default: tool_use

        • id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • input: map[unknown]

        • name: string

          minLength: 1

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

            • type: "direct"

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

            • type: "code_execution_20250825"

            • tool_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

          • BetaServerToolCaller20260120 object

            • type: "code_execution_20260120"

            • tool_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • toolset_name: optional string or null

          For a toolset member tool_use, the toolset family.

          maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

      • BetaServerToolUseBlock object

        • type: "server_tool_use"

          default: server_tool_use

        • id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • input: map[unknown]

        • name: "advisor" or "web_search" or "web_fetch" or 5 more

          • "advisor"

          • "web_search"

          • "web_fetch"

          • "code_execution"

          • "bash_code_execution"

          • "text_editor_code_execution"

          • "tool_search_tool_regex"

          • "tool_search_tool_bm25"

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaWebSearchToolResultBlock object

        • type: "web_search_tool_result"

          default: web_search_tool_result

        • content: BetaWebSearchToolResultBlockContent

          • BetaWebSearchToolResultError object

            • type: "web_search_tool_result_error"

              default: web_search_tool_result_error

            • error_code: BetaWebSearchToolResultErrorCode

              • "invalid_tool_input"

              • "unavailable"

              • "max_uses_exceeded"

              • "too_many_requests"

              • "query_too_long"

              • "request_too_large"

          • array of BetaWebSearchResultBlock

            • type: "web_search_result"

              default: web_search_result

            • encrypted_content: string

            • page_age: string or null

            • title: string

            • url: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaWebFetchToolResultBlock object

        • type: "web_fetch_tool_result"

          default: web_fetch_tool_result

        • content: BetaWebFetchToolResultErrorBlock or BetaWebFetchBlock

          • BetaWebFetchToolResultErrorBlock object

            • type: "web_fetch_tool_result_error"

              default: web_fetch_tool_result_error

            • error_code: BetaWebFetchToolResultErrorCode

              • "invalid_tool_input"

              • "url_too_long"

              • "url_not_allowed"

              • "url_not_in_prior_context"

              • "url_not_accessible"

              • "unsupported_content_type"

              • "too_many_requests"

              • "max_uses_exceeded"

              • "unavailable"

              • "content_too_large"

          • BetaWebFetchBlock object

            • type: "web_fetch_result"

              default: web_fetch_result

            • content: BetaDocumentBlock

              • type: "document"

                default: document

              • citations: BetaCitationConfig or null

                Citation configuration for the document

                • enabled: boolean

                  default: false

              • source: BetaBase64PDFSource or BetaPlainTextSource

                • BetaBase64PDFSource object

                  • type: "base64"

                  • data: string

                    format: byte

                  • media_type: "application/pdf"

                • BetaPlainTextSource object

                  • type: "text"

                  • data: string

                  • media_type: "text/plain"

              • title: string or null

                The title of the document

            • retrieved_at: string or null

              ISO 8601 timestamp when the content was retrieved

            • url: string

              Fetched content URL

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

          Tool invocation directly from the model.

          • BetaDirectCaller object

            Tool invocation directly from the model.

          • BetaServerToolCaller object

            Tool invocation generated by a server-side tool.

          • BetaServerToolCaller20260120 object

      • BetaAdvisorToolResultBlock object

        • type: "advisor_tool_result"

          default: advisor_tool_result

        • content: BetaAdvisorToolResultError or BetaAdvisorResultBlock or BetaAdvisorRedactedResultBlock

          • BetaAdvisorToolResultError object

            • type: "advisor_tool_result_error"

              default: advisor_tool_result_error

            • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

              • "max_uses_exceeded"

              • "prompt_too_long"

              • "too_many_requests"

              • "overloaded"

              • "unavailable"

              • "execution_time_exceeded"

              • "model_not_found"

          • BetaAdvisorResultBlock object

            • type: "advisor_result"

              default: advisor_result

            • stop_reason: string or null

              The advisor sub-inference's stop reason (same values as the top-level message stop_reason). max_tokens indicates the advisor's output was truncated at the tool's max_tokens value or the advisor model's policy cap.

            • text: string

          • BetaAdvisorRedactedResultBlock object

            • type: "advisor_redacted_result"

              default: advisor_redacted_result

            • encrypted_content: string

              Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

            • stop_reason: string or null

              The advisor sub-inference's stop reason (same values as the top-level message stop_reason).

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • BetaCodeExecutionToolResultBlock object

        • type: "code_execution_tool_result"

          default: code_execution_tool_result

        • content: BetaCodeExecutionToolResultBlockContent

          Code execution result with encrypted stdout for PFC + web_search results.

          • BetaCodeExecutionToolResultError object

            • type: "code_execution_tool_result_error"

              default: code_execution_tool_result_error

            • error_code: BetaCodeExecutionToolResultErrorCode

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

          • BetaCodeExecutionResultBlock object

            • type: "code_execution_result"

              default: code_execution_result

            • content: array of BetaCodeExecutionOutputBlock

              • type: "code_execution_output"

                default: code_execution_output

              • file_id: string

            • return_code: number

            • stderr: string

            • stdout: string

          • BetaEncryptedCodeExecutionResultBlock object

            Code execution result with encrypted stdout for PFC + web_search results.

            • type: "encrypted_code_execution_result"

              default: encrypted_code_execution_result

            • content: array of BetaCodeExecutionOutputBlock

              • type: "code_execution_output"

                default: code_execution_output

              • file_id: string

            • encrypted_stdout: string

            • return_code: number

            • stderr: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • BetaBashCodeExecutionToolResultBlock object

        • type: "bash_code_execution_tool_result"

          default: bash_code_execution_tool_result

        • content: BetaBashCodeExecutionToolResultError or BetaBashCodeExecutionResultBlock

          • BetaBashCodeExecutionToolResultError object

            • type: "bash_code_execution_tool_result_error"

              default: bash_code_execution_tool_result_error

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

              • "output_file_too_large"

          • BetaBashCodeExecutionResultBlock object

            • type: "bash_code_execution_result"

              default: bash_code_execution_result

            • content: array of BetaBashCodeExecutionOutputBlock

              • type: "bash_code_execution_output"

                default: bash_code_execution_output

              • file_id: string

            • return_code: number

            • stderr: string

            • stdout: string

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • BetaTextEditorCodeExecutionToolResultBlock object

        • type: "text_editor_code_execution_tool_result"

          default: text_editor_code_execution_tool_result

        • content: BetaTextEditorCodeExecutionToolResultError or BetaTextEditorCodeExecutionViewResultBlock or BetaTextEditorCodeExecutionCreateResultBlock or BetaTextEditorCodeExecutionStrReplaceResultBlock

          • BetaTextEditorCodeExecutionToolResultError object

            • type: "text_editor_code_execution_tool_result_error"

              default: text_editor_code_execution_tool_result_error

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

              • "file_not_found"

            • error_message: string or null

          • BetaTextEditorCodeExecutionViewResultBlock object

            • type: "text_editor_code_execution_view_result"

              default: text_editor_code_execution_view_result

            • content: string

            • file_type: "text" or "image" or "pdf"

              • "text"

              • "image"

              • "pdf"

            • num_lines: number or null

            • start_line: number or null

            • total_lines: number or null

          • BetaTextEditorCodeExecutionCreateResultBlock object

            • type: "text_editor_code_execution_create_result"

              default: text_editor_code_execution_create_result

            • is_file_update: boolean

          • BetaTextEditorCodeExecutionStrReplaceResultBlock object

            • type: "text_editor_code_execution_str_replace_result"

              default: text_editor_code_execution_str_replace_result

            • lines: array of string or null

            • new_lines: number or null

            • new_start: number or null

            • old_lines: number or null

            • old_start: number or null

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • BetaToolSearchToolResultBlock object

        • type: "tool_search_tool_result"

          default: tool_search_tool_result

        • content: BetaToolSearchToolResultError or BetaToolSearchToolSearchResultBlock

          • BetaToolSearchToolResultError object

            • type: "tool_search_tool_result_error"

              default: tool_search_tool_result_error

            • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

              • "invalid_tool_input"

              • "unavailable"

              • "too_many_requests"

              • "execution_time_exceeded"

            • error_message: string or null

          • BetaToolSearchToolSearchResultBlock object

            • type: "tool_search_tool_search_result"

              default: tool_search_tool_search_result

            • tool_references: array of BetaToolReferenceBlock

              • type: "tool_reference"

                default: tool_reference

              • tool_name: string

                maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

        • tool_use_id: string

          pattern: ^srvtoolu_[a-zA-Z0-9_]+$

      • BetaMCPToolUseBlock object

        • type: "mcp_tool_use"

          default: mcp_tool_use

        • id: string

          pattern: ^[a-zA-Z0-9_-]+$

        • input: map[unknown]

        • name: string

          The name of the MCP tool

        • server_name: string

          The name of the MCP server

      • BetaMCPToolResultBlock object

        • type: "mcp_tool_result"

          default: mcp_tool_result

        • content: string or array of BetaTextBlock

          • string

          • BetaMCPToolResultBlockContent = array of BetaTextBlock

            • type: "text"

              default: text

            • citations: array of BetaTextCitation or null

              Citations supporting the text block.

              The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

            • text: string

              minLength: 0

        • is_error: boolean

          default: false

        • tool_use_id: string

          pattern: ^[a-zA-Z0-9_-]+$

      • BetaContainerUploadBlock object

        Response model for a file uploaded to the container.

        • type: "container_upload"

          default: container_upload

        • file_id: string

      • BetaCompactionBlock object

        A compaction block returned when autocompact is triggered.

        When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

        • type: "compaction"

          default: compaction

        • content: string or null

          Summary of compacted content, or null if compaction failed

        • encrypted_content: string or null

          Opaque metadata from prior compaction, to be round-tripped verbatim

      • BetaFallbackBlock object

        Marks the point in content where one model's output gives way to the next.

        One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

        The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

        • type: "fallback"

          default: fallback

        • from: BetaFallbackInfo

          The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its model echoes the top-level model string the caller sent (alias or canonical); when the declining hop is a fallback model, its model is that model's canonical id.

          • model: Model

            The model that will complete your prompt.

            See models for additional details and options.

            • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

              The model that will complete your prompt.

              See models for additional details and options.

              • "claude-fable-5-1"

                Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

              • "claude-mythos-5-1"

                Our most capable model for cybersecurity and biology research, available through trusted access programs

              • "claude-sonnet-5"

                High-performance model for coding and agents

              • "claude-fable-5"

                Next generation of intelligence for the hardest knowledge work and coding problems

              • "claude-mythos-5"

                Most capable model for cybersecurity and biology research

              • "claude-opus-5"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-8"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-7"

                Powerful intelligence for long-running agents and coding

              • "claude-mythos-preview"

                New class of intelligence, strongest in coding and cybersecurity

              • "claude-opus-4-6"

                Powerful intelligence for long-running agents and coding

              • "claude-sonnet-4-6"

                Best combination of speed and intelligence

              • "claude-haiku-4-5"

                Fastest model with near-frontier intelligence

              • "claude-haiku-4-5-20251001"

                Fastest model with near-frontier intelligence

              • "claude-opus-4-5"

                Powerful intelligence for long-running agents and coding

              • "claude-opus-4-5-20251101"

                Powerful intelligence for long-running agents and coding

              • "claude-sonnet-4-5"

                High-performance model for agents and coding

              • "claude-sonnet-4-5-20250929"

                High-performance model for agents and coding

            • string

        • to: BetaFallbackInfo

          The fallback model producing the content that follows this block. Its model is always the canonical id.

        • trigger: BetaFallbackRefusalTrigger

          What caused the from model to hand over at this hop.

          • type: "refusal"

            default: refusal

          • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

            The policy category that triggered a refusal.

            • "cyber"

              The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

            • "bio"

              The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

            • "frontier_llm"

              The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

            • "reasoning_extraction"

              The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

            • "general_harms"

              The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

    • context_management: BetaContextManagementResponse or null

      Context management response.

      Information about context management strategies applied during the request.

      • applied_edits: array of BetaClearToolUses20250919EditResponse or BetaClearThinking20251015EditResponse

        List of context management edits that were applied.

        • BetaClearToolUses20250919EditResponse object

          • type: "clear_tool_uses_20250919"

            The type of context management edit applied.

            default: clear_tool_uses_20250919

          • cleared_input_tokens: number

            Number of input tokens cleared by this edit.

            minimum: 0

          • cleared_tool_uses: number

            Number of tool uses that were cleared.

            minimum: 0

        • BetaClearThinking20251015EditResponse object

          • type: "clear_thinking_20251015"

            The type of context management edit applied.

            default: clear_thinking_20251015

          • cleared_input_tokens: number

            Number of input tokens cleared by this edit.

            minimum: 0

          • cleared_thinking_turns: number

            Number of thinking turns that were cleared.

            minimum: 0

    • diagnostics: BetaDiagnostics or null

      Response envelope for request-level diagnostics. Present (possibly null) whenever the caller supplied diagnostics on the request.

      • cache_miss_reason: BetaCacheMissModelChanged or BetaCacheMissSystemChanged or BetaCacheMissToolsChanged or 3 more or null

        Explains why the prompt cache could not fully reuse the prefix from the request identified by diagnostics.previous_message_id. null means diagnosis is still pending — the response was serialized before the background comparison completed.

        • BetaCacheMissModelChanged object

          • type: "model_changed"

            default: model_changed

          • cache_missed_input_tokens: number

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        • BetaCacheMissSystemChanged object

          • type: "system_changed"

            default: system_changed

          • cache_missed_input_tokens: number

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        • BetaCacheMissToolsChanged object

          • type: "tools_changed"

            default: tools_changed

          • cache_missed_input_tokens: number

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        • BetaCacheMissMessagesChanged object

          • type: "messages_changed"

            default: messages_changed

          • cache_missed_input_tokens: number

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        • BetaCacheMissPreviousMessageNotFound object

          • type: "previous_message_not_found"

            default: previous_message_not_found

        • BetaCacheMissUnavailable object

          • type: "unavailable"

            default: unavailable

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

    • role: "assistant"

      Conversational role of the generated message.

      This will always be "assistant".

      default: assistant

    • stop_details: BetaRefusalStopDetails or null

      Structured information about a refusal.

      • type: "refusal"

        default: refusal

      • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

        The policy category that triggered a refusal.

        • "cyber"

          The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

        • "bio"

          The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

        • "frontier_llm"

          The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

        • "reasoning_extraction"

          The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

        • "general_harms"

          The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

      • explanation: string or null

        Human-readable explanation of the refusal.

        This text is not guaranteed to be stable. null when no explanation is available for the category.

      • fallback_credit_token: string or null

        Opaque code that refunds the cache-miss cost when retrying this refused request on the fallback model. Pass it as fallback_credit_token on the retry request. Expires 5 minutes after the refusal.

        The retry is sent either with the same request body (system, messages, tools, and other render-shaping fields), or with the same body plus one appended assistant message whose content is the partial text (with any trailing whitespace stripped from the final text block) and paired server-tool blocks from this refusal — which also authorizes that appended turn as an assistant-prefill continuation on models that otherwise disallow prefill. A token minted mid-server-tool-loop whose partial content was continuable may only be redeemed the second way — if a same-body retry is rejected with a 400 saying the token must be redeemed by continuing the partial response, retry the second way instead. Either way: same workspace, same platform; a mismatch is a 400. Resending a token for an already-warm prefix is permitted but yields no additional credit.

        null when the refused model isn't eligible for a fallback credit.

      • fallback_has_prefill_claim: boolean or null

        Whether the accompanying fallback_credit_token may be redeemed with the appended-assistant retry form. Only set when fallback_credit_token is present.

        true: retry by resending the same request body plus one appended assistant message whose content is this response's content with any trailing whitespace stripped from the final text block and unpaired tool_use blocks omitted (the same appended-turn shape described on fallback_credit_token), with the token attached. false: retry by resending the original request body unchanged, with the token attached — the appended-assistant form is not available for this refusal (no continuable partial content, or the request uses output_format or a tool_choice that forces tool use). One exception: when the request used output_format or a forced tool_choice and the refusal arrived after server tools (including MCP connector tools) had already executed, the token may not be redeemable by either retry form; if the exact-body retry is then rejected with a 400 saying the token must be redeemed by continuing the partial response, discard the token and retry without it.

        Advisory: if an appended-assistant retry is rejected with a 400 despite true, fall back to resending the original request body with the token.

      • recommended_model: string or null

        The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

    • stop_reason: BetaStopReason or null

      The reason that we stopped.

      This may be one the following values:

      • "end_turn": the model reached a natural stopping point
      • "max_tokens": we exceeded the requested max_tokens or the model's maximum
      • "stop_sequence": one of your provided custom stop_sequences was generated
      • "tool_use": the model invoked one or more tools
      • "pause_turn": we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
      • "refusal": when streaming classifiers intervene to handle potential policy violations
      • "model_context_window_exceeded": we exceeded the model's context window

      In non-streaming mode this value is always non-null. In streaming mode, it is null in the message_start event and non-null otherwise.

      • "end_turn"

      • "max_tokens"

      • "stop_sequence"

      • "tool_use"

      • "pause_turn"

      • "compaction"

      • "refusal"

      • "model_context_window_exceeded"

    • stop_sequence: string or null

      Which custom stop sequence was generated, if any.

      This value will be a non-null string if one of your custom stop sequences was generated.

    • usage: BetaUsage

      Billing and rate-limit usage.

      Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

      Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in usage will not match one-to-one with the exact visible content of an API request or response.

      For example, output_tokens will be non-zero, even for an empty string response from Claude.

      Total input tokens in a request is the summation of input_tokens, cache_creation_input_tokens, and cache_read_input_tokens.

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

        • ephemeral_1h_input_tokens: number

          The number of input tokens used to create the 1 hour cache entry.

          default: 0, minimum: 0

        • ephemeral_5m_input_tokens: number

          The number of input tokens used to create the 5 minute cache entry.

          default: 0, minimum: 0

      • cache_creation_input_tokens: number or null

        The number of input tokens used to create the cache entry.

        minimum: 0

      • cache_read_input_tokens: number or null

        The number of input tokens read from the cache.

        minimum: 0

      • fallback_credit: BetaFallbackCreditUsage or null

        Outcome of the fallback_credit_token presented on this request.

        • status: BetaFallbackCreditRedeemed or BetaFallbackCreditNotApplied

          Whether the fallback-credit reprice was applied to this response's billing.

          A union discriminated on type. redeemed: the retry is billed as if the conversation had been on the retry model all along — including when the resulting shift is zero because there was nothing to move. not_applied: no reprice was applied; the arm's reason says why.

          • BetaFallbackCreditRedeemed object

            The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

            • type: "redeemed"

              default: redeemed

          • BetaFallbackCreditNotApplied object

            No reprice was applied; reason says why.

            • type: "not_applied"

              default: not_applied

            • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

              Why the reprice was not applied.

              A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

              • "body_mismatch"

              • "continuation_excluded"

              • "continuation_only"

              • "expired"

              • "invalid_target_model"

              • "not_enabled"

              • "reprice_unavailable"

              • "temporarily_unavailable"

              • "variant_fields_present"

              • "wrong_organization"

              • "wrong_platform"

              • "wrong_workspace"

            • remove_to_redeem: optional array of string or null

              Request fields to remove before retrying, so the retry can redeem this token.

              Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

      • inference_geo: string or null

        The geographic region where inference was performed for this request.

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • iterations: BetaIterationsUsage or null

        Per-iteration token usage breakdown.

        Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

        • Determine which iterations exceeded long context thresholds (>=200k tokens)
        • Calculate the context window size from the last message entry
        • Understand token accumulation across server-side tool use loops

        A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

        • BetaMessageIterationUsage object

          Token usage for a sampling iteration.

          • type: "message"

            Usage for a sampling iteration

            default: message

          • cache_creation: BetaCacheCreation or null

            Breakdown of cached tokens by TTL

          • cache_creation_input_tokens: number

            The number of input tokens used to create the cache entry.

            default: 0, minimum: 0

          • cache_read_input_tokens: number

            The number of input tokens read from the cache.

            default: 0, minimum: 0

          • input_tokens: number

            The number of input tokens which were used.

            minimum: 0

          • model: Model

            The model that will complete your prompt.

            See models for additional details and options.

          • output_tokens: number

            The number of output tokens which were used.

            minimum: 0

        • BetaCompactionIterationUsage object

          Token usage for a compaction iteration.

          • type: "compaction"

            Usage for a compaction iteration

            default: compaction

          • cache_creation: BetaCacheCreation or null

            Breakdown of cached tokens by TTL

          • cache_creation_input_tokens: number

            The number of input tokens used to create the cache entry.

            default: 0, minimum: 0

          • cache_read_input_tokens: number

            The number of input tokens read from the cache.

            default: 0, minimum: 0

          • input_tokens: number

            The number of input tokens which were used.

            minimum: 0

          • output_tokens: number

            The number of output tokens which were used.

            minimum: 0

        • BetaAdvisorMessageIterationUsage object

          Token usage for an advisor sub-inference iteration.

          • type: "advisor_message"

            Usage for an advisor sub-inference iteration

            default: advisor_message

          • cache_creation: BetaCacheCreation or null

            Breakdown of cached tokens by TTL

          • cache_creation_input_tokens: number

            The number of input tokens used to create the cache entry.

            default: 0, minimum: 0

          • cache_read_input_tokens: number

            The number of input tokens read from the cache.

            default: 0, minimum: 0

          • input_tokens: number

            The number of input tokens which were used.

            minimum: 0

          • model: Model

            The model that will complete your prompt.

            See models for additional details and options.

          • output_tokens: number

            The number of output tokens which were used.

            minimum: 0

        • BetaFallbackMessageIterationUsage object

          Token usage for the fallback-model attempt of a server-side fallback request.

          Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

          • type: "fallback_message"

            Usage for the fallback-model attempt that served the response

            default: fallback_message

          • cache_creation: BetaCacheCreation or null

            Breakdown of cached tokens by TTL

          • cache_creation_input_tokens: number

            The number of input tokens used to create the cache entry.

            default: 0, minimum: 0

          • cache_read_input_tokens: number

            The number of input tokens read from the cache.

            default: 0, minimum: 0

          • input_tokens: number

            The number of input tokens which were used.

            minimum: 0

          • model: Model

            The model that will complete your prompt.

            See models for additional details and options.

          • output_tokens: number

            The number of output tokens which were used.

            minimum: 0

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

      • output_tokens_details: BetaOutputTokensDetails or null

        Breakdown of output tokens by category.

        output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

        • thinking_tokens: number

          Number of output tokens the model generated as internal reasoning, including the thinking-block delimiter tokens.

          Reflects the raw reasoning the model produced, not the (possibly shorter) summarized thinking text returned in the response body. Computed by re-tokenizing the raw reasoning text, so it may differ from the model's exact generation count by a small number of tokens. Always ≤ output_tokens; output_tokens - thinking_tokens approximates the non-reasoning output.

          default: 0, minimum: 0

      • server_tool_use: BetaServerToolUsage or null

        The number of server tool requests.

        • web_fetch_requests: number

          The number of web fetch tool requests.

          default: 0, minimum: 0

        • web_search_requests: number

          The number of web search tool requests.

          default: 0, minimum: 0

      • service_tier: "standard" or "priority" or "batch" or null

        If the request used the priority, standard, or batch tier.

        • "standard"

        • "priority"

        • "batch"

      • speed: "standard" or "fast" or null

        Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

        • "standard"

        • "fast"

    • input_transformations: optional array of BetaThinkingDroppedInputTransformation or null

      Changes the API made to the request's input before showing it to the model: one entry per change, in request order. Today the only entry type is thinking_dropped — a thinking, redacted_thinking or connector_text block from the request's messages that was removed from the prompt instead of being shown to the model because it failed a binding check. More entry types may be added over time; ignore types you do not recognize.

      Requires anthropic-beta: thinking-binding-controls-2026-08-01. Present on every such response from a model that supports extended thinking, as [] when nothing was changed; without the beta, blocks are removed all the same but nothing is reported. Removed blocks contribute nothing to usage.input_tokens. When streaming, the array is final in message_start; the final message_delta event carries it only when a server-side model fallback happened mid-stream, in which case it holds the serving model's entries and replaces the one in message_start.

      • type: "thinking_dropped"

        Always thinking_dropped for this entry type.

        default: thinking_dropped

      • path: string

        Where the removed block was in your request, as messages.\{i\}.content.\{j\}: i indexes the messages array you sent and j that message's content array — the same form error messages use.

      • reason: "model_binding_mismatch" or "prefix_binding_mismatch" or "organization_binding_mismatch" or "end_user_binding_mismatch"

        Which binding check removed the block: model_binding_mismatch — it was created by a model whose reasoning the requested model may not read; prefix_binding_mismatch — the conversation before it differs from the conversation it was created in (the rest of that turn's consecutive thinking blocks are removed with it, each with this reason); organization_binding_mismatch — it was created under a different organization (an Anthropic organization, AWS account or Google Cloud project) and this organization is not one of its additional organizations; end_user_binding_mismatch — it was created for a different end user, or was removed by the consumer-organization binding. A block that would fail several checks reports one reason, in this order of precedence: organization_binding_mismatch, end_user_binding_mismatch, model_binding_mismatch, prefix_binding_mismatch.

        • "model_binding_mismatch"

        • "prefix_binding_mismatch"

        • "organization_binding_mismatch"

        • "end_user_binding_mismatch"

Beta Raw Message Stop Event

• BetaRawMessageStopEvent object

  • type: "message_stop"

    default: message_stop

Beta Raw Message Stream Event

• BetaRawMessageStreamEvent = BetaRawMessageStartEvent or BetaRawMessageDeltaEvent or BetaRawMessageStopEvent or 3 more

  • BetaRawMessageStartEvent object

    • type: "message_start"

      default: message_start

    • message: BetaMessage

      • type: "message"

        Object type.

        For Messages, this is always "message".

        default: message

      • id: string

        Unique object identifier.

        The format and length of IDs may change over time.

      • container: BetaContainer or null

        Information about the container used in the request (for the code execution tool)

        • id: string

          Identifier for the container used in this request

        • expires_at: string

          The time at which the container will expire.

          format: date-time

        • skills: array of BetaContainerSkill or null

          Skills loaded in the container

          • type: "anthropic" or "custom"

            Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

            • "anthropic"

            • "custom"

          • skill_id: string

            Skill ID

            maxLength: 64, minLength: 1

          • version: string

            The resolved version: a skill version ID for custom skills.

            maxLength: 64, minLength: 1

      • content: array of BetaContentBlock

        Content generated by the model.

        This is an array of content blocks, each of which has a type that determines its shape.

        Example:

        [\{"type": "text", "text": "Hi, I'm Claude."\}]

        If the request input messages ended with an assistant turn, then the response content will continue directly from that last turn. You can use this to constrain the model's output.

        For example, if the input messages were:

        [
          \{"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"\},
          \{"role": "assistant", "content": "The best answer is ("\}
        ]

        Then the response content might be:

        [\{"type": "text", "text": "B)"\}]

        • BetaTextBlock object

          • type: "text"

            default: text

          • citations: array of BetaTextCitation or null

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

            • BetaCitationCharLocation object

              • type: "char_location"

                default: char_location

              • cited_text: string

              • document_index: number

                minimum: 0

              • document_title: string or null

              • end_char_index: number

              • file_id: string or null

              • start_char_index: number

                minimum: 0

            • BetaCitationPageLocation object

              • type: "page_location"

                default: page_location

              • cited_text: string

              • document_index: number

                minimum: 0

              • document_title: string or null

              • end_page_number: number

              • file_id: string or null

              • start_page_number: number

                minimum: 1

            • BetaCitationContentBlockLocation object

              • type: "content_block_location"

                default: content_block_location

              • cited_text: string

                The full text of the cited block range, concatenated.

                Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

              • document_index: number

                minimum: 0

              • document_title: string or null

              • end_block_index: number

                Exclusive 0-based end index of the cited block range in the source's content array.

                Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

              • file_id: string or null

              • start_block_index: number

                0-based index of the first cited block in the source's content array.

                minimum: 0

            • BetaCitationsWebSearchResultLocation object

              • type: "web_search_result_location"

                default: web_search_result_location

              • cited_text: string

              • encrypted_index: string

              • title: string or null

                maxLength: 512

              • url: string

            • BetaCitationSearchResultLocation object

              • type: "search_result_location"

                default: search_result_location

              • cited_text: string

                The full text of the cited block range, concatenated.

                Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

              • end_block_index: number

                Exclusive 0-based end index of the cited block range in the source's content array.

                Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

              • search_result_index: number

                0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

                Counted separately from document_index; server-side web search results are not included in this count.

                minimum: 0

              • source: string

              • start_block_index: number

                0-based index of the first cited block in the source's content array.

                minimum: 0

              • title: string or null

          • text: string

            minLength: 0

        • BetaThinkingBlock object

          • type: "thinking"

            default: thinking

          • signature: string

            A value used to verify that this thinking block was generated by Claude when it is passed back to the API.

            This is an opaque field and should not be interpreted or parsed. When passing thinking blocks back to the API (required when using tools with extended thinking), pass them back exactly as received, with this field intact.

            See extended thinking for details.

          • thinking: string

            The text of Claude's thinking process for this block.

        • BetaRedactedThinkingBlock object

          • type: "redacted_thinking"

            default: redacted_thinking

          • data: string

            The contents of this redacted thinking block, returned when portions of the model's thinking were safety-redacted. This field is opaque and encrypted, with no readable content.

            Pass redacted_thinking blocks back to the API unchanged when continuing a multi-turn conversation.

            See extended thinking for details.

        • BetaToolUseBlock object

          • type: "tool_use"

            default: tool_use

          • id: string

            pattern: ^[a-zA-Z0-9_-]+$

          • input: map[unknown]

          • name: string

            minLength: 1

          • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

            Tool invocation directly from the model.

            • BetaDirectCaller object

              Tool invocation directly from the model.

              • type: "direct"

            • BetaServerToolCaller object

              Tool invocation generated by a server-side tool.

              • type: "code_execution_20250825"

              • tool_id: string

                pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • BetaServerToolCaller20260120 object

              • type: "code_execution_20260120"

              • tool_id: string

                pattern: ^srvtoolu_[a-zA-Z0-9_]+$

          • toolset_name: optional string or null

            For a toolset member tool_use, the toolset family.

            maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

        • BetaServerToolUseBlock object

          • type: "server_tool_use"

            default: server_tool_use

          • id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

          • input: map[unknown]

          • name: "advisor" or "web_search" or "web_fetch" or 5 more

            • "advisor"

            • "web_search"

            • "web_fetch"

            • "code_execution"

            • "bash_code_execution"

            • "text_editor_code_execution"

            • "tool_search_tool_regex"

            • "tool_search_tool_bm25"

          • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

            Tool invocation directly from the model.

            • BetaDirectCaller object

              Tool invocation directly from the model.

            • BetaServerToolCaller object

              Tool invocation generated by a server-side tool.

            • BetaServerToolCaller20260120 object

        • BetaWebSearchToolResultBlock object

          • type: "web_search_tool_result"

            default: web_search_tool_result

          • content: BetaWebSearchToolResultBlockContent

            • BetaWebSearchToolResultError object

              • type: "web_search_tool_result_error"

                default: web_search_tool_result_error

              • error_code: BetaWebSearchToolResultErrorCode

                • "invalid_tool_input"

                • "unavailable"

                • "max_uses_exceeded"

                • "too_many_requests"

                • "query_too_long"

                • "request_too_large"

            • array of BetaWebSearchResultBlock

              • type: "web_search_result"

                default: web_search_result

              • encrypted_content: string

              • page_age: string or null

              • title: string

              • url: string

          • tool_use_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

          • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

            Tool invocation directly from the model.

            • BetaDirectCaller object

              Tool invocation directly from the model.

            • BetaServerToolCaller object

              Tool invocation generated by a server-side tool.

            • BetaServerToolCaller20260120 object

        • BetaWebFetchToolResultBlock object

          • type: "web_fetch_tool_result"

            default: web_fetch_tool_result

          • content: BetaWebFetchToolResultErrorBlock or BetaWebFetchBlock

            • BetaWebFetchToolResultErrorBlock object

              • type: "web_fetch_tool_result_error"

                default: web_fetch_tool_result_error

              • error_code: BetaWebFetchToolResultErrorCode

                • "invalid_tool_input"

                • "url_too_long"

                • "url_not_allowed"

                • "url_not_in_prior_context"

                • "url_not_accessible"

                • "unsupported_content_type"

                • "too_many_requests"

                • "max_uses_exceeded"

                • "unavailable"

                • "content_too_large"

            • BetaWebFetchBlock object

              • type: "web_fetch_result"

                default: web_fetch_result

              • content: BetaDocumentBlock

                • type: "document"

                  default: document

                • citations: BetaCitationConfig or null

                  Citation configuration for the document

                  • enabled: boolean

                    default: false

                • source: BetaBase64PDFSource or BetaPlainTextSource

                  • BetaBase64PDFSource object

                    • type: "base64"

                    • data: string

                      format: byte

                    • media_type: "application/pdf"

                  • BetaPlainTextSource object

                    • type: "text"

                    • data: string

                    • media_type: "text/plain"

                • title: string or null

                  The title of the document

              • retrieved_at: string or null

                ISO 8601 timestamp when the content was retrieved

              • url: string

                Fetched content URL

          • tool_use_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

          • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

            Tool invocation directly from the model.

            • BetaDirectCaller object

              Tool invocation directly from the model.

            • BetaServerToolCaller object

              Tool invocation generated by a server-side tool.

            • BetaServerToolCaller20260120 object

        • BetaAdvisorToolResultBlock object

          • type: "advisor_tool_result"

            default: advisor_tool_result

          • content: BetaAdvisorToolResultError or BetaAdvisorResultBlock or BetaAdvisorRedactedResultBlock

            • BetaAdvisorToolResultError object

              • type: "advisor_tool_result_error"

                default: advisor_tool_result_error

              • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

                • "max_uses_exceeded"

                • "prompt_too_long"

                • "too_many_requests"

                • "overloaded"

                • "unavailable"

                • "execution_time_exceeded"

                • "model_not_found"

            • BetaAdvisorResultBlock object

              • type: "advisor_result"

                default: advisor_result

              • stop_reason: string or null

                The advisor sub-inference's stop reason (same values as the top-level message stop_reason). max_tokens indicates the advisor's output was truncated at the tool's max_tokens value or the advisor model's policy cap.

              • text: string

            • BetaAdvisorRedactedResultBlock object

              • type: "advisor_redacted_result"

                default: advisor_redacted_result

              • encrypted_content: string

                Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

              • stop_reason: string or null

                The advisor sub-inference's stop reason (same values as the top-level message stop_reason).

          • tool_use_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • BetaCodeExecutionToolResultBlock object

          • type: "code_execution_tool_result"

            default: code_execution_tool_result

          • content: BetaCodeExecutionToolResultBlockContent

            Code execution result with encrypted stdout for PFC + web_search results.

            • BetaCodeExecutionToolResultError object

              • type: "code_execution_tool_result_error"

                default: code_execution_tool_result_error

              • error_code: BetaCodeExecutionToolResultErrorCode

                • "invalid_tool_input"

                • "unavailable"

                • "too_many_requests"

                • "execution_time_exceeded"

            • BetaCodeExecutionResultBlock object

              • type: "code_execution_result"

                default: code_execution_result

              • content: array of BetaCodeExecutionOutputBlock

                • type: "code_execution_output"

                  default: code_execution_output

                • file_id: string

              • return_code: number

              • stderr: string

              • stdout: string

            • BetaEncryptedCodeExecutionResultBlock object

              Code execution result with encrypted stdout for PFC + web_search results.

              • type: "encrypted_code_execution_result"

                default: encrypted_code_execution_result

              • content: array of BetaCodeExecutionOutputBlock

                • type: "code_execution_output"

                  default: code_execution_output

                • file_id: string

              • encrypted_stdout: string

              • return_code: number

              • stderr: string

          • tool_use_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • BetaBashCodeExecutionToolResultBlock object

          • type: "bash_code_execution_tool_result"

            default: bash_code_execution_tool_result

          • content: BetaBashCodeExecutionToolResultError or BetaBashCodeExecutionResultBlock

            • BetaBashCodeExecutionToolResultError object

              • type: "bash_code_execution_tool_result_error"

                default: bash_code_execution_tool_result_error

              • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

                • "invalid_tool_input"

                • "unavailable"

                • "too_many_requests"

                • "execution_time_exceeded"

                • "output_file_too_large"

            • BetaBashCodeExecutionResultBlock object

              • type: "bash_code_execution_result"

                default: bash_code_execution_result

              • content: array of BetaBashCodeExecutionOutputBlock

                • type: "bash_code_execution_output"

                  default: bash_code_execution_output

                • file_id: string

              • return_code: number

              • stderr: string

              • stdout: string

          • tool_use_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • BetaTextEditorCodeExecutionToolResultBlock object

          • type: "text_editor_code_execution_tool_result"

            default: text_editor_code_execution_tool_result

          • content: BetaTextEditorCodeExecutionToolResultError or BetaTextEditorCodeExecutionViewResultBlock or BetaTextEditorCodeExecutionCreateResultBlock or BetaTextEditorCodeExecutionStrReplaceResultBlock

            • BetaTextEditorCodeExecutionToolResultError object

              • type: "text_editor_code_execution_tool_result_error"

                default: text_editor_code_execution_tool_result_error

              • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

                • "invalid_tool_input"

                • "unavailable"

                • "too_many_requests"

                • "execution_time_exceeded"

                • "file_not_found"

              • error_message: string or null

            • BetaTextEditorCodeExecutionViewResultBlock object

              • type: "text_editor_code_execution_view_result"

                default: text_editor_code_execution_view_result

              • content: string

              • file_type: "text" or "image" or "pdf"

                • "text"

                • "image"

                • "pdf"

              • num_lines: number or null

              • start_line: number or null

              • total_lines: number or null

            • BetaTextEditorCodeExecutionCreateResultBlock object

              • type: "text_editor_code_execution_create_result"

                default: text_editor_code_execution_create_result

              • is_file_update: boolean

            • BetaTextEditorCodeExecutionStrReplaceResultBlock object

              • type: "text_editor_code_execution_str_replace_result"

                default: text_editor_code_execution_str_replace_result

              • lines: array of string or null

              • new_lines: number or null

              • new_start: number or null

              • old_lines: number or null

              • old_start: number or null

          • tool_use_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • BetaToolSearchToolResultBlock object

          • type: "tool_search_tool_result"

            default: tool_search_tool_result

          • content: BetaToolSearchToolResultError or BetaToolSearchToolSearchResultBlock

            • BetaToolSearchToolResultError object

              • type: "tool_search_tool_result_error"

                default: tool_search_tool_result_error

              • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

                • "invalid_tool_input"

                • "unavailable"

                • "too_many_requests"

                • "execution_time_exceeded"

              • error_message: string or null

            • BetaToolSearchToolSearchResultBlock object

              • type: "tool_search_tool_search_result"

                default: tool_search_tool_search_result

              • tool_references: array of BetaToolReferenceBlock

                • type: "tool_reference"

                  default: tool_reference

                • tool_name: string

                  maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

          • tool_use_id: string

            pattern: ^srvtoolu_[a-zA-Z0-9_]+$

        • BetaMCPToolUseBlock object

          • type: "mcp_tool_use"

            default: mcp_tool_use

          • id: string

            pattern: ^[a-zA-Z0-9_-]+$

          • input: map[unknown]

          • name: string

            The name of the MCP tool

          • server_name: string

            The name of the MCP server

        • BetaMCPToolResultBlock object

          • type: "mcp_tool_result"

            default: mcp_tool_result

          • content: string or array of BetaTextBlock

            • string

            • BetaMCPToolResultBlockContent = array of BetaTextBlock

              • type: "text"

                default: text

              • citations: array of BetaTextCitation or null

                Citations supporting the text block.

                The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

              • text: string

                minLength: 0

          • is_error: boolean

            default: false

          • tool_use_id: string

            pattern: ^[a-zA-Z0-9_-]+$

        • BetaContainerUploadBlock object

          Response model for a file uploaded to the container.

          • type: "container_upload"

            default: container_upload

          • file_id: string

        • BetaCompactionBlock object

          A compaction block returned when autocompact is triggered.

          When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

          • type: "compaction"

            default: compaction

          • content: string or null

            Summary of compacted content, or null if compaction failed

          • encrypted_content: string or null

            Opaque metadata from prior compaction, to be round-tripped verbatim

        • BetaFallbackBlock object

          Marks the point in content where one model's output gives way to the next.

          One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

          The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

          • type: "fallback"

            default: fallback

          • from: BetaFallbackInfo

            The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its model echoes the top-level model string the caller sent (alias or canonical); when the declining hop is a fallback model, its model is that model's canonical id.

            • model: Model

              The model that will complete your prompt.

              See models for additional details and options.

              • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

                The model that will complete your prompt.

                See models for additional details and options.

                • "claude-fable-5-1"

                  Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

                • "claude-mythos-5-1"

                  Our most capable model for cybersecurity and biology research, available through trusted access programs

                • "claude-sonnet-5"

                  High-performance model for coding and agents

                • "claude-fable-5"

                  Next generation of intelligence for the hardest knowledge work and coding problems

                • "claude-mythos-5"

                  Most capable model for cybersecurity and biology research

                • "claude-opus-5"

                  Powerful intelligence for long-running agents and coding

                • "claude-opus-4-8"

                  Powerful intelligence for long-running agents and coding

                • "claude-opus-4-7"

                  Powerful intelligence for long-running agents and coding

                • "claude-mythos-preview"

                  New class of intelligence, strongest in coding and cybersecurity

                • "claude-opus-4-6"

                  Powerful intelligence for long-running agents and coding

                • "claude-sonnet-4-6"

                  Best combination of speed and intelligence

                • "claude-haiku-4-5"

                  Fastest model with near-frontier intelligence

                • "claude-haiku-4-5-20251001"

                  Fastest model with near-frontier intelligence

                • "claude-opus-4-5"

                  Powerful intelligence for long-running agents and coding

                • "claude-opus-4-5-20251101"

                  Powerful intelligence for long-running agents and coding

                • "claude-sonnet-4-5"

                  High-performance model for agents and coding

                • "claude-sonnet-4-5-20250929"

                  High-performance model for agents and coding

              • string

          • to: BetaFallbackInfo

            The fallback model producing the content that follows this block. Its model is always the canonical id.

          • trigger: BetaFallbackRefusalTrigger

            What caused the from model to hand over at this hop.

            • type: "refusal"

              default: refusal

            • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

              The policy category that triggered a refusal.

              • "cyber"

                The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

              • "bio"

                The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

              • "frontier_llm"

                The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

              • "reasoning_extraction"

                The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

              • "general_harms"

                The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

      • context_management: BetaContextManagementResponse or null

        Context management response.

        Information about context management strategies applied during the request.

        • applied_edits: array of BetaClearToolUses20250919EditResponse or BetaClearThinking20251015EditResponse

          List of context management edits that were applied.

          • BetaClearToolUses20250919EditResponse object

            • type: "clear_tool_uses_20250919"

              The type of context management edit applied.

              default: clear_tool_uses_20250919

            • cleared_input_tokens: number

              Number of input tokens cleared by this edit.

              minimum: 0

            • cleared_tool_uses: number

              Number of tool uses that were cleared.

              minimum: 0

          • BetaClearThinking20251015EditResponse object

            • type: "clear_thinking_20251015"

              The type of context management edit applied.

              default: clear_thinking_20251015

            • cleared_input_tokens: number

              Number of input tokens cleared by this edit.

              minimum: 0

            • cleared_thinking_turns: number

              Number of thinking turns that were cleared.

              minimum: 0

      • diagnostics: BetaDiagnostics or null

        Response envelope for request-level diagnostics. Present (possibly null) whenever the caller supplied diagnostics on the request.

        • cache_miss_reason: BetaCacheMissModelChanged or BetaCacheMissSystemChanged or BetaCacheMissToolsChanged or 3 more or null

          Explains why the prompt cache could not fully reuse the prefix from the request identified by diagnostics.previous_message_id. null means diagnosis is still pending — the response was serialized before the background comparison completed.

          • BetaCacheMissModelChanged object

            • type: "model_changed"

              default: model_changed

            • cache_missed_input_tokens: number

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          • BetaCacheMissSystemChanged object

            • type: "system_changed"

              default: system_changed

            • cache_missed_input_tokens: number

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          • BetaCacheMissToolsChanged object

            • type: "tools_changed"

              default: tools_changed

            • cache_missed_input_tokens: number

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          • BetaCacheMissMessagesChanged object

            • type: "messages_changed"

              default: messages_changed

            • cache_missed_input_tokens: number

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          • BetaCacheMissPreviousMessageNotFound object

            • type: "previous_message_not_found"

              default: previous_message_not_found

          • BetaCacheMissUnavailable object

            • type: "unavailable"

              default: unavailable

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

      • role: "assistant"

        Conversational role of the generated message.

        This will always be "assistant".

        default: assistant

      • stop_details: BetaRefusalStopDetails or null

        Structured information about a refusal.

        • type: "refusal"

          default: refusal

        • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

          The policy category that triggered a refusal.

          • "cyber"

            The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

          • "bio"

            The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

          • "frontier_llm"

            The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

          • "reasoning_extraction"

            The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

          • "general_harms"

            The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

        • explanation: string or null

          Human-readable explanation of the refusal.

          This text is not guaranteed to be stable. null when no explanation is available for the category.

        • fallback_credit_token: string or null

          Opaque code that refunds the cache-miss cost when retrying this refused request on the fallback model. Pass it as fallback_credit_token on the retry request. Expires 5 minutes after the refusal.

          The retry is sent either with the same request body (system, messages, tools, and other render-shaping fields), or with the same body plus one appended assistant message whose content is the partial text (with any trailing whitespace stripped from the final text block) and paired server-tool blocks from this refusal — which also authorizes that appended turn as an assistant-prefill continuation on models that otherwise disallow prefill. A token minted mid-server-tool-loop whose partial content was continuable may only be redeemed the second way — if a same-body retry is rejected with a 400 saying the token must be redeemed by continuing the partial response, retry the second way instead. Either way: same workspace, same platform; a mismatch is a 400. Resending a token for an already-warm prefix is permitted but yields no additional credit.

          null when the refused model isn't eligible for a fallback credit.

        • fallback_has_prefill_claim: boolean or null

          Whether the accompanying fallback_credit_token may be redeemed with the appended-assistant retry form. Only set when fallback_credit_token is present.

          true: retry by resending the same request body plus one appended assistant message whose content is this response's content with any trailing whitespace stripped from the final text block and unpaired tool_use blocks omitted (the same appended-turn shape described on fallback_credit_token), with the token attached. false: retry by resending the original request body unchanged, with the token attached — the appended-assistant form is not available for this refusal (no continuable partial content, or the request uses output_format or a tool_choice that forces tool use). One exception: when the request used output_format or a forced tool_choice and the refusal arrived after server tools (including MCP connector tools) had already executed, the token may not be redeemable by either retry form; if the exact-body retry is then rejected with a 400 saying the token must be redeemed by continuing the partial response, discard the token and retry without it.

          Advisory: if an appended-assistant retry is rejected with a 400 despite true, fall back to resending the original request body with the token.

        • recommended_model: string or null

          The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

      • stop_reason: BetaStopReason or null

        The reason that we stopped.

        This may be one the following values:

        • "end_turn": the model reached a natural stopping point
        • "max_tokens": we exceeded the requested max_tokens or the model's maximum
        • "stop_sequence": one of your provided custom stop_sequences was generated
        • "tool_use": the model invoked one or more tools
        • "pause_turn": we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
        • "refusal": when streaming classifiers intervene to handle potential policy violations
        • "model_context_window_exceeded": we exceeded the model's context window

        In non-streaming mode this value is always non-null. In streaming mode, it is null in the message_start event and non-null otherwise.

        • "end_turn"

        • "max_tokens"

        • "stop_sequence"

        • "tool_use"

        • "pause_turn"

        • "compaction"

        • "refusal"

        • "model_context_window_exceeded"

      • stop_sequence: string or null

        Which custom stop sequence was generated, if any.

        This value will be a non-null string if one of your custom stop sequences was generated.

      • usage: BetaUsage

        Billing and rate-limit usage.

        Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

        Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in usage will not match one-to-one with the exact visible content of an API request or response.

        For example, output_tokens will be non-zero, even for an empty string response from Claude.

        Total input tokens in a request is the summation of input_tokens, cache_creation_input_tokens, and cache_read_input_tokens.

        • cache_creation: BetaCacheCreation or null

          Breakdown of cached tokens by TTL

          • ephemeral_1h_input_tokens: number

            The number of input tokens used to create the 1 hour cache entry.

            default: 0, minimum: 0

          • ephemeral_5m_input_tokens: number

            The number of input tokens used to create the 5 minute cache entry.

            default: 0, minimum: 0

        • cache_creation_input_tokens: number or null

          The number of input tokens used to create the cache entry.

          minimum: 0

        • cache_read_input_tokens: number or null

          The number of input tokens read from the cache.

          minimum: 0

        • fallback_credit: BetaFallbackCreditUsage or null

          Outcome of the fallback_credit_token presented on this request.

          • status: BetaFallbackCreditRedeemed or BetaFallbackCreditNotApplied

            Whether the fallback-credit reprice was applied to this response's billing.

            A union discriminated on type. redeemed: the retry is billed as if the conversation had been on the retry model all along — including when the resulting shift is zero because there was nothing to move. not_applied: no reprice was applied; the arm's reason says why.

            • BetaFallbackCreditRedeemed object

              The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

              • type: "redeemed"

                default: redeemed

            • BetaFallbackCreditNotApplied object

              No reprice was applied; reason says why.

              • type: "not_applied"

                default: not_applied

              • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

                Why the reprice was not applied.

                A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

                • "body_mismatch"

                • "continuation_excluded"

                • "continuation_only"

                • "expired"

                • "invalid_target_model"

                • "not_enabled"

                • "reprice_unavailable"

                • "temporarily_unavailable"

                • "variant_fields_present"

                • "wrong_organization"

                • "wrong_platform"

                • "wrong_workspace"

              • remove_to_redeem: optional array of string or null

                Request fields to remove before retrying, so the retry can redeem this token.

                Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

        • inference_geo: string or null

          The geographic region where inference was performed for this request.

        • input_tokens: number

          The number of input tokens which were used.

          minimum: 0

        • iterations: BetaIterationsUsage or null

          Per-iteration token usage breakdown.

          Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

          • Determine which iterations exceeded long context thresholds (>=200k tokens)
          • Calculate the context window size from the last message entry
          • Understand token accumulation across server-side tool use loops

          A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

          • BetaMessageIterationUsage object

            Token usage for a sampling iteration.

            • type: "message"

              Usage for a sampling iteration

              default: message

            • cache_creation: BetaCacheCreation or null

              Breakdown of cached tokens by TTL

            • cache_creation_input_tokens: number

              The number of input tokens used to create the cache entry.

              default: 0, minimum: 0

            • cache_read_input_tokens: number

              The number of input tokens read from the cache.

              default: 0, minimum: 0

            • input_tokens: number

              The number of input tokens which were used.

              minimum: 0

            • model: Model

              The model that will complete your prompt.

              See models for additional details and options.

            • output_tokens: number

              The number of output tokens which were used.

              minimum: 0

          • BetaCompactionIterationUsage object

            Token usage for a compaction iteration.

            • type: "compaction"

              Usage for a compaction iteration

              default: compaction

            • cache_creation: BetaCacheCreation or null

              Breakdown of cached tokens by TTL

            • cache_creation_input_tokens: number

              The number of input tokens used to create the cache entry.

              default: 0, minimum: 0

            • cache_read_input_tokens: number

              The number of input tokens read from the cache.

              default: 0, minimum: 0

            • input_tokens: number

              The number of input tokens which were used.

              minimum: 0

            • output_tokens: number

              The number of output tokens which were used.

              minimum: 0

          • BetaAdvisorMessageIterationUsage object

            Token usage for an advisor sub-inference iteration.

            • type: "advisor_message"

              Usage for an advisor sub-inference iteration

              default: advisor_message

            • cache_creation: BetaCacheCreation or null

              Breakdown of cached tokens by TTL

            • cache_creation_input_tokens: number

              The number of input tokens used to create the cache entry.

              default: 0, minimum: 0

            • cache_read_input_tokens: number

              The number of input tokens read from the cache.

              default: 0, minimum: 0

            • input_tokens: number

              The number of input tokens which were used.

              minimum: 0

            • model: Model

              The model that will complete your prompt.

              See models for additional details and options.

            • output_tokens: number

              The number of output tokens which were used.

              minimum: 0

          • BetaFallbackMessageIterationUsage object

            Token usage for the fallback-model attempt of a server-side fallback request.

            Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

            • type: "fallback_message"

              Usage for the fallback-model attempt that served the response

              default: fallback_message

            • cache_creation: BetaCacheCreation or null

              Breakdown of cached tokens by TTL

            • cache_creation_input_tokens: number

              The number of input tokens used to create the cache entry.

              default: 0, minimum: 0

            • cache_read_input_tokens: number

              The number of input tokens read from the cache.

              default: 0, minimum: 0

            • input_tokens: number

              The number of input tokens which were used.

              minimum: 0

            • model: Model

              The model that will complete your prompt.

              See models for additional details and options.

            • output_tokens: number

              The number of output tokens which were used.

              minimum: 0

        • output_tokens: number

          The number of output tokens which were used.

          minimum: 0

        • output_tokens_details: BetaOutputTokensDetails or null

          Breakdown of output tokens by category.

          output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

          • thinking_tokens: number

            Number of output tokens the model generated as internal reasoning, including the thinking-block delimiter tokens.

            Reflects the raw reasoning the model produced, not the (possibly shorter) summarized thinking text returned in the response body. Computed by re-tokenizing the raw reasoning text, so it may differ from the model's exact generation count by a small number of tokens. Always ≤ output_tokens; output_tokens - thinking_tokens approximates the non-reasoning output.

            default: 0, minimum: 0

        • server_tool_use: BetaServerToolUsage or null

          The number of server tool requests.

          • web_fetch_requests: number

            The number of web fetch tool requests.

            default: 0, minimum: 0

          • web_search_requests: number

            The number of web search tool requests.

            default: 0, minimum: 0

        • service_tier: "standard" or "priority" or "batch" or null

          If the request used the priority, standard, or batch tier.

          • "standard"

          • "priority"

          • "batch"

        • speed: "standard" or "fast" or null

          Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

          • "standard"

          • "fast"

      • input_transformations: optional array of BetaThinkingDroppedInputTransformation or null

        Changes the API made to the request's input before showing it to the model: one entry per change, in request order. Today the only entry type is thinking_dropped — a thinking, redacted_thinking or connector_text block from the request's messages that was removed from the prompt instead of being shown to the model because it failed a binding check. More entry types may be added over time; ignore types you do not recognize.

        Requires anthropic-beta: thinking-binding-controls-2026-08-01. Present on every such response from a model that supports extended thinking, as [] when nothing was changed; without the beta, blocks are removed all the same but nothing is reported. Removed blocks contribute nothing to usage.input_tokens. When streaming, the array is final in message_start; the final message_delta event carries it only when a server-side model fallback happened mid-stream, in which case it holds the serving model's entries and replaces the one in message_start.

        • type: "thinking_dropped"

          Always thinking_dropped for this entry type.

          default: thinking_dropped

        • path: string

          Where the removed block was in your request, as messages.{i}.content.{j}: i indexes the messages array you sent and j that message's content array — the same form error messages use.

        • reason: "model_binding_mismatch" or "prefix_binding_mismatch" or "organization_binding_mismatch" or "end_user_binding_mismatch"

          Which binding check removed the block: model_binding_mismatch — it was created by a model whose reasoning the requested model may not read; prefix_binding_mismatch — the conversation before it differs from the conversation it was created in (the rest of that turn's consecutive thinking blocks are removed with it, each with this reason); organization_binding_mismatch — it was created under a different organization (an Anthropic organization, AWS account or Google Cloud project) and this organization is not one of its additional organizations; end_user_binding_mismatch — it was created for a different end user, or was removed by the consumer-organization binding. A block that would fail several checks reports one reason, in this order of precedence: organization_binding_mismatch, end_user_binding_mismatch, model_binding_mismatch, prefix_binding_mismatch.

          • "model_binding_mismatch"

          • "prefix_binding_mismatch"

          • "organization_binding_mismatch"

          • "end_user_binding_mismatch"

  • BetaRawMessageDeltaEvent object

    • type: "message_delta"

      default: message_delta

    • context_management: BetaContextManagementResponse or null

      Information about context management strategies applied during the request

    • delta: object

      • container: BetaContainer or null

        Information about the container used in the request (for the code execution tool)

      • stop_details: BetaRefusalStopDetails or null

        Structured information about a refusal.

      • stop_reason: BetaStopReason or null

      • stop_sequence: string or null

    • usage: BetaMessageDeltaUsage

      Billing and rate-limit usage.

      Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

      Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in usage will not match one-to-one with the exact visible content of an API request or response.

      For example, output_tokens will be non-zero, even for an empty string response from Claude.

      Total input tokens in a request is the summation of input_tokens, cache_creation_input_tokens, and cache_read_input_tokens.

      • cache_creation_input_tokens: number or null

        The cumulative number of input tokens used to create the cache entry.

        minimum: 0

      • cache_read_input_tokens: number or null

        The cumulative number of input tokens read from the cache.

        minimum: 0

      • fallback_credit: BetaFallbackCreditUsage or null

        Outcome of the fallback_credit_token presented on this request.

      • input_tokens: number or null

        The cumulative number of input tokens which were used.

        minimum: 0

      • iterations: BetaIterationsUsage or null

        Per-iteration token usage breakdown.

        Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

        • Determine which iterations exceeded long context thresholds (>=200k tokens)
        • Calculate the context window size from the last message entry
        • Understand token accumulation across server-side tool use loops

        A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

      • output_tokens: number

        The cumulative number of output tokens which were used.

      • output_tokens_details: BetaOutputTokensDetails or null

        Breakdown of output tokens by category.

        output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

      • server_tool_use: BetaServerToolUsage or null

        The number of server tool requests.

    • input_transformations: optional array of BetaThinkingDroppedInputTransformation or null

      Changes the API made to the request's input before showing it to the model: one entry per change, in request order. Today the only entry type is thinking_dropped — a thinking, redacted_thinking or connector_text block from the request's messages that was removed from the prompt instead of being shown to the model because it failed a binding check. More entry types may be added over time; ignore types you do not recognize.

      Requires anthropic-beta: thinking-binding-controls-2026-08-01. Present on every such response from a model that supports extended thinking, as [] when nothing was changed; without the beta, blocks are removed all the same but nothing is reported. Removed blocks contribute nothing to usage.input_tokens. When streaming, the array is final in message_start; the final message_delta event carries it only when a server-side model fallback happened mid-stream, in which case it holds the serving model's entries and replaces the one in message_start.

      • type: "thinking_dropped"

        Always thinking_dropped for this entry type.

        default: thinking_dropped

      • path: string

        Where the removed block was in your request, as messages.{i}.content.{j}: i indexes the messages array you sent and j that message's content array — the same form error messages use.

      • reason: "model_binding_mismatch" or "prefix_binding_mismatch" or "organization_binding_mismatch" or "end_user_binding_mismatch"

        Which binding check removed the block: model_binding_mismatch — it was created by a model whose reasoning the requested model may not read; prefix_binding_mismatch — the conversation before it differs from the conversation it was created in (the rest of that turn's consecutive thinking blocks are removed with it, each with this reason); organization_binding_mismatch — it was created under a different organization (an Anthropic organization, AWS account or Google Cloud project) and this organization is not one of its additional organizations; end_user_binding_mismatch — it was created for a different end user, or was removed by the consumer-organization binding. A block that would fail several checks reports one reason, in this order of precedence: organization_binding_mismatch, end_user_binding_mismatch, model_binding_mismatch, prefix_binding_mismatch.

  • BetaRawMessageStopEvent object

    • type: "message_stop"

      default: message_stop

  • BetaRawContentBlockStartEvent object

    • type: "content_block_start"

      default: content_block_start

    • content_block: BetaTextBlock or BetaThinkingBlock or BetaRedactedThinkingBlock or 14 more

      Response model for a file uploaded to the container.

      • BetaTextBlock object

      • BetaThinkingBlock object

      • BetaRedactedThinkingBlock object

      • BetaToolUseBlock object

      • BetaServerToolUseBlock object

      • BetaWebSearchToolResultBlock object

      • BetaWebFetchToolResultBlock object

      • BetaAdvisorToolResultBlock object

      • BetaCodeExecutionToolResultBlock object

      • BetaBashCodeExecutionToolResultBlock object

      • BetaTextEditorCodeExecutionToolResultBlock object

      • BetaToolSearchToolResultBlock object

      • BetaMCPToolUseBlock object

      • BetaMCPToolResultBlock object

      • BetaContainerUploadBlock object

        Response model for a file uploaded to the container.

      • BetaCompactionBlock object

        A compaction block returned when autocompact is triggered.

        When content is None, it indicates the compaction failed to produce a valid summary (e.g., malformed output from the model). Clients may round-trip compaction blocks with null content; the server treats them as no-ops.

      • BetaFallbackBlock object

        Marks the point in content where one model's output gives way to the next.

        One block appears per hop where a preceding model actually ran this turn and declined. A turn where no preceding model ran and declined has no such boundary and carries no block — the signal for whether a fallback model served the response is the presence of a fallback_message entry in usage.iterations, not this block.

        The block is treated like a server-tool content block for streaming: it arrives via the standard content_block_start / content_block_stop pair and carries no deltas.

    • index: number

  • BetaRawContentBlockDeltaEvent object

    • type: "content_block_delta"

      default: content_block_delta

    • delta: BetaRawContentBlockDelta

      • BetaTextDelta object

        • type: "text_delta"

          default: text_delta

        • text: string

      • BetaInputJSONDelta object

        • type: "input_json_delta"

          default: input_json_delta

        • partial_json: string

      • BetaCitationsDelta object

        • type: "citations_delta"

          default: citations_delta

        • citation: BetaCitationCharLocation or BetaCitationPageLocation or BetaCitationContentBlockLocation or 2 more

          • BetaCitationCharLocation object

          • BetaCitationPageLocation object

          • BetaCitationContentBlockLocation object

          • BetaCitationsWebSearchResultLocation object

          • BetaCitationSearchResultLocation object

      • BetaThinkingDelta object

        • type: "thinking_delta"

          default: thinking_delta

        • estimated_tokens: number or null

          Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the thinking-token-count-2026-05-13 beta is set; null unless thinking.display resolves to "omitted" and a count is due this frame. Sum the increments across thinking_delta frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; usage.output_tokens remains authoritative.

        • thinking: string

          The incremental thinking text for this content block. Concatenate the thinking values of successive thinking_delta events to assemble the block's full thinking value.

      • BetaSignatureDelta object

        • type: "signature_delta"

          default: signature_delta

        • signature: string

          The signature for this thinking block: an opaque value used to verify that the block was generated by Claude when it is passed back to the API. Delivered in a signature_delta event just before the block's content_block_stop event.

      • BetaCompactionContentBlockDelta object

        • type: "compaction_delta"

          default: compaction_delta

        • content: string or null

        • encrypted_content: string or null

          Opaque metadata from prior compaction, to be round-tripped verbatim

    • index: number

  • BetaRawContentBlockStopEvent object

    • type: "content_block_stop"

      default: content_block_stop

    • index: number

Beta Redacted Thinking Block

• BetaRedactedThinkingBlock object

  • type: "redacted_thinking"

    default: redacted_thinking

  • data: string

    The contents of this redacted thinking block, returned when portions of the model's thinking were safety-redacted. This field is opaque and encrypted, with no readable content.

    Pass redacted_thinking blocks back to the API unchanged when continuing a multi-turn conversation.

    See extended thinking for details.

Beta Redacted Thinking Block Param

• BetaRedactedThinkingBlockParam object

  • type: "redacted_thinking"

  • data: string

    The data value of this redacted thinking block, exactly as returned by the API in a previous response. Opaque and encrypted; pass it back unchanged.

Beta Refusal Stop Details

• BetaRefusalStopDetails object

  Structured information about a refusal.

  • type: "refusal"

    default: refusal

  • category: "cyber" or "bio" or "frontier_llm" or 2 more or null

    The policy category that triggered a refusal.

    • "cyber"

      The request could enable cyber harm, such as malware or exploit development. Benign cybersecurity work can also trigger this category.

    • "bio"

      The request could enable biological harm, such as dangerous lab methods. Beneficial life sciences work can also trigger this category.

    • "frontier_llm"

      The request could assist the development of competing AI models, which is restricted under Anthropic's commercial terms. Benign machine learning work can also trigger this category.

    • "reasoning_extraction"

      The request asks the model to reproduce its internal reasoning in the response text. To get reasoning in a structured form instead, use adaptive thinking.

    • "general_harms"

      The request could be related to an area that was determined as harmful. Benign work might sometimes trigger this category.

  • explanation: string or null

    Human-readable explanation of the refusal.

    This text is not guaranteed to be stable. null when no explanation is available for the category.

  • fallback_credit_token: string or null

    Opaque code that refunds the cache-miss cost when retrying this refused request on the fallback model. Pass it as fallback_credit_token on the retry request. Expires 5 minutes after the refusal.

    The retry is sent either with the same request body (system, messages, tools, and other render-shaping fields), or with the same body plus one appended assistant message whose content is the partial text (with any trailing whitespace stripped from the final text block) and paired server-tool blocks from this refusal — which also authorizes that appended turn as an assistant-prefill continuation on models that otherwise disallow prefill. A token minted mid-server-tool-loop whose partial content was continuable may only be redeemed the second way — if a same-body retry is rejected with a 400 saying the token must be redeemed by continuing the partial response, retry the second way instead. Either way: same workspace, same platform; a mismatch is a 400. Resending a token for an already-warm prefix is permitted but yields no additional credit.

    null when the refused model isn't eligible for a fallback credit.

  • fallback_has_prefill_claim: boolean or null

    Whether the accompanying fallback_credit_token may be redeemed with the appended-assistant retry form. Only set when fallback_credit_token is present.

    true: retry by resending the same request body plus one appended assistant message whose content is this response's content with any trailing whitespace stripped from the final text block and unpaired tool_use blocks omitted (the same appended-turn shape described on fallback_credit_token), with the token attached. false: retry by resending the original request body unchanged, with the token attached — the appended-assistant form is not available for this refusal (no continuable partial content, or the request uses output_format or a tool_choice that forces tool use). One exception: when the request used output_format or a forced tool_choice and the refusal arrived after server tools (including MCP connector tools) had already executed, the token may not be redeemable by either retry form; if the exact-body retry is then rejected with a 400 saying the token must be redeemed by continuing the partial response, discard the token and retry without it.

    Advisory: if an appended-assistant retry is rejected with a 400 despite true, fall back to resending the original request body with the token.

  • recommended_model: string or null

    The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

Beta Request Document Block

• BetaRequestDocumentBlock object

  • type: "document"

  • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

    • BetaBase64PDFSource object

      • type: "base64"

      • data: string

        format: byte

      • media_type: "application/pdf"

    • BetaPlainTextSource object

      • type: "text"

      • data: string

      • media_type: "text/plain"

    • BetaContentBlockSource object

      • type: "content"

      • content: string or array of BetaContentBlockSourceContent

        • string

        • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

          • BetaTextBlockParam object

            • type: "text"

            • text: string

              minLength: 1

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

              • type: "ephemeral"

              • ttl: optional "5m" or "1h"

                The time-to-live for the cache control breakpoint.

                This may be one the following values:

                • 5m: 5 minutes
                • 1h: 1 hour

                Defaults to 5m. See prompt caching pricing for details.

                • "5m"

                • "1h"

            • citations: optional array of BetaTextCitationParam or null

              • BetaCitationCharLocationParam object

                • type: "char_location"

                • cited_text: string

                • document_index: number

                  minimum: 0

                • document_title: string or null

                  maxLength: 500, minLength: 1

                • end_char_index: number

                • start_char_index: number

                  minimum: 0

              • BetaCitationPageLocationParam object

                • type: "page_location"

                • cited_text: string

                • document_index: number

                  minimum: 0

                • document_title: string or null

                  maxLength: 500, minLength: 1

                • end_page_number: number

                • start_page_number: number

                  minimum: 1

              • BetaCitationContentBlockLocationParam object

                • type: "content_block_location"

                • cited_text: string

                  The full text of the cited block range, concatenated.

                  Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                • document_index: number

                  minimum: 0

                • document_title: string or null

                  maxLength: 500, minLength: 1

                • end_block_index: number

                  Exclusive 0-based end index of the cited block range in the source's content array.

                  Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

                • start_block_index: number

                  0-based index of the first cited block in the source's content array.

                  minimum: 0

              • BetaCitationWebSearchResultLocationParam object

                • type: "web_search_result_location"

                • cited_text: string

                • encrypted_index: string

                • title: string or null

                  maxLength: 512, minLength: 1

                • url: string

                  minLength: 1

              • BetaCitationSearchResultLocationParam object

                • type: "search_result_location"

                • cited_text: string

                  The full text of the cited block range, concatenated.

                  Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                • end_block_index: number

                  Exclusive 0-based end index of the cited block range in the source's content array.

                  Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

                • search_result_index: number

                  0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

                  Counted separately from document_index; server-side web search results are not included in this count.

                  minimum: 0

                • source: string

                • start_block_index: number

                  0-based index of the first cited block in the source's content array.

                  minimum: 0

                • title: string or null

          • BetaImageBlockParam object

            • type: "image"

            • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

              • BetaBase64ImageSource object

                • type: "base64"

                • data: string

                  format: byte

                • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

                  • "image/jpeg"

                  • "image/png"

                  • "image/gif"

                  • "image/webp"

              • BetaURLImageSource object

                • type: "url"

                • url: string

              • BetaFileImageSource object

                • type: "file"

                • file_id: string

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • transformations: optional BetaImageTransformationsParam or null

              Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

              • oversized_image: optional "downsize" or "error"

                What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

                • "downsize"

                • "error"

    • BetaURLPDFSource object

      • type: "url"

      • url: string

    • BetaFileDocumentSource object

      • type: "file"

      • file_id: string

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

  • citations: optional BetaCitationsConfigParam or null

    • enabled: optional boolean

  • context: optional string or null

    minLength: 1

  • title: optional string or null

    maxLength: 500, minLength: 1

Beta Request MCP Server Tool Configuration

• BetaRequestMCPServerToolConfiguration object

  • allowed_tools: optional array of string or null

  • enabled: optional boolean or null

Beta Request MCP Server URL Definition

• BetaRequestMCPServerURLDefinition object

  • type: "url"

  • name: string

  • url: string

  • authorization_token: optional string or null

  • tool_configuration: optional BetaRequestMCPServerToolConfiguration or null

    • allowed_tools: optional array of string or null

    • enabled: optional boolean or null

Beta Request MCP Tool Result Block Param

• BetaRequestMCPToolResultBlockParam object

  • type: "mcp_tool_result"

  • tool_use_id: string

    pattern: ^[a-zA-Z0-9_-]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • content: optional string or array of BetaTextBlockParam

    • string

    • BetaMCPToolResultBlockParamContent = array of BetaTextBlockParam

      • type: "text"

      • text: string

        minLength: 1

      • cache_control: optional BetaCacheControlEphemeral or null

        Create a cache control breakpoint at this content block.

      • citations: optional array of BetaTextCitationParam or null

        • BetaCitationCharLocationParam object

          • type: "char_location"

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

            maxLength: 500, minLength: 1

          • end_char_index: number

          • start_char_index: number

            minimum: 0

        • BetaCitationPageLocationParam object

          • type: "page_location"

          • cited_text: string

          • document_index: number

            minimum: 0

          • document_title: string or null

            maxLength: 500, minLength: 1

          • end_page_number: number

          • start_page_number: number

            minimum: 1

        • BetaCitationContentBlockLocationParam object

          • type: "content_block_location"

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • document_index: number

            minimum: 0

          • document_title: string or null

            maxLength: 500, minLength: 1

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

        • BetaCitationWebSearchResultLocationParam object

          • type: "web_search_result_location"

          • cited_text: string

          • encrypted_index: string

          • title: string or null

            maxLength: 512, minLength: 1

          • url: string

            minLength: 1

        • BetaCitationSearchResultLocationParam object

          • type: "search_result_location"

          • cited_text: string

            The full text of the cited block range, concatenated.

            Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          • end_block_index: number

            Exclusive 0-based end index of the cited block range in the source's content array.

            Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

          • search_result_index: number

            0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from document_index; server-side web search results are not included in this count.

            minimum: 0

          • source: string

          • start_block_index: number

            0-based index of the first cited block in the source's content array.

            minimum: 0

          • title: string or null

  • is_error: optional boolean

Beta Request Tool Addition Block

• BetaRequestToolAdditionBlock object

  Mid-conversation directive to surface a declared tool.

  tool references a tool (or MCP toolset) by name from the request's tools; it is offered to the model from this point in the conversation onward.

  • type: "tool_addition"

  • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

    Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

    • BetaToolChangeToolReference object

      Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

      • type: "tool_reference"

      • name: string

        pattern: ^[a-zA-Z0-9_-]{1,128}$

    • BetaToolChangeMCPToolReference object

      Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

      • type: "mcp_tool_reference"

      • name: string

      • server_name: string

    • BetaToolChangeMCPToolsetReference object

      Reference to every tool in the named MCP server's toolset.

      • type: "mcp_toolset_reference"

      • server_name: string

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta Request Tool Removal Block

• BetaRequestToolRemovalBlock object

  Mid-conversation directive to withdraw a tool.

  tool references a tool (or MCP toolset) by name from the request's tools; it is no longer offered to the model from this point in the conversation onward.

  • type: "tool_removal"

  • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

    Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

    • BetaToolChangeToolReference object

      Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

      • type: "tool_reference"

      • name: string

        pattern: ^[a-zA-Z0-9_-]{1,128}$

    • BetaToolChangeMCPToolReference object

      Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

      • type: "mcp_tool_reference"

      • name: string

      • server_name: string

    • BetaToolChangeMCPToolsetReference object

      Reference to every tool in the named MCP server's toolset.

      • type: "mcp_toolset_reference"

      • server_name: string

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta Search Result Block Param

• BetaSearchResultBlockParam object

  • type: "search_result"

  • content: array of BetaTextBlockParam

    • type: "text"

    • text: string

      minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

      • type: "ephemeral"

      • ttl: optional "5m" or "1h"

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        • 5m: 5 minutes
        • 1h: 1 hour

        Defaults to 5m. See prompt caching pricing for details.

        • "5m"

        • "1h"

    • citations: optional array of BetaTextCitationParam or null

      • BetaCitationCharLocationParam object

        • type: "char_location"

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_char_index: number

        • start_char_index: number

          minimum: 0

      • BetaCitationPageLocationParam object

        • type: "page_location"

        • cited_text: string

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_page_number: number

        • start_page_number: number

          minimum: 1

      • BetaCitationContentBlockLocationParam object

        • type: "content_block_location"

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • document_index: number

          minimum: 0

        • document_title: string or null

          maxLength: 500, minLength: 1

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

      • BetaCitationWebSearchResultLocationParam object

        • type: "web_search_result_location"

        • cited_text: string

        • encrypted_index: string

        • title: string or null

          maxLength: 512, minLength: 1

        • url: string

          minLength: 1

      • BetaCitationSearchResultLocationParam object

        • type: "search_result_location"

        • cited_text: string

          The full text of the cited block range, concatenated.

          Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        • end_block_index: number

          Exclusive 0-based end index of the cited block range in the source's content array.

          Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

        • search_result_index: number

          0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from document_index; server-side web search results are not included in this count.

          minimum: 0

        • source: string

        • start_block_index: number

          0-based index of the first cited block in the source's content array.

          minimum: 0

        • title: string or null

  • source: string

  • title: string

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

  • citations: optional BetaCitationsConfigParam

    • enabled: optional boolean

Beta Server Tool Caller

• BetaServerToolCaller object

  Tool invocation generated by a server-side tool.

  • type: "code_execution_20250825"

  • tool_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Server Tool Caller 20260120

• BetaServerToolCaller20260120 object

  • type: "code_execution_20260120"

  • tool_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Server Tool Usage

• BetaServerToolUsage object

  • web_fetch_requests: number

    The number of web fetch tool requests.

    default: 0, minimum: 0

  • web_search_requests: number

    The number of web search tool requests.

    default: 0, minimum: 0

Beta Server Tool Use Block

• BetaServerToolUseBlock object

  • type: "server_tool_use"

    default: server_tool_use

  • id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • input: map[unknown]

  • name: "advisor" or "web_search" or "web_fetch" or 5 more

    • "advisor"

    • "web_search"

    • "web_fetch"

    • "code_execution"

    • "bash_code_execution"

    • "text_editor_code_execution"

    • "tool_search_tool_regex"

    • "tool_search_tool_bm25"

  • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

    Tool invocation directly from the model.

    • BetaDirectCaller object

      Tool invocation directly from the model.

      • type: "direct"

    • BetaServerToolCaller object

      Tool invocation generated by a server-side tool.

      • type: "code_execution_20250825"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaServerToolCaller20260120 object

      • type: "code_execution_20260120"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Server Tool Use Block Param

• BetaServerToolUseBlockParam object

  • type: "server_tool_use"

  • id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • input: map[unknown]

  • name: "advisor" or "web_search" or "web_fetch" or 5 more

    • "advisor"

    • "web_search"

    • "web_fetch"

    • "code_execution"

    • "bash_code_execution"

    • "text_editor_code_execution"

    • "tool_search_tool_regex"

    • "tool_search_tool_bm25"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

    Tool invocation directly from the model.

    • BetaDirectCaller object

      Tool invocation directly from the model.

      • type: "direct"

    • BetaServerToolCaller object

      Tool invocation generated by a server-side tool.

      • type: "code_execution_20250825"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaServerToolCaller20260120 object

      • type: "code_execution_20260120"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Signature Delta

• BetaSignatureDelta object

  • type: "signature_delta"

    default: signature_delta

  • signature: string

    The signature for this thinking block: an opaque value used to verify that the block was generated by Claude when it is passed back to the API. Delivered in a signature_delta event just before the block's content_block_stop event.

Beta Skill Params

• BetaSkillParams object

  Specification for a skill to be loaded in a container (request model).

  • type: "anthropic" or "custom"

    Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

    • "anthropic"

    • "custom"

  • skill_id: string

    Skill ID

    maxLength: 64, minLength: 1

  • version: optional string

    Skill version or 'latest' for most recent version

    maxLength: 64, minLength: 1

Beta Stop Reason

• BetaStopReason = "end_turn" or "max_tokens" or "stop_sequence" or 5 more

  • "end_turn"

  • "max_tokens"

  • "stop_sequence"

  • "tool_use"

  • "pause_turn"

  • "compaction"

  • "refusal"

  • "model_context_window_exceeded"

Beta System Message Output Config

• BetaSystemMessageOutputConfig object

  Per-message output configuration on a role:"system" input message.

  Fields here apply per-turn; format remains top-level only. An empty \{\} is accepted on a message that carries content; a message with neither content nor output_config fields is rejected.

  • effort: optional "low" or "medium" or "high" or 2 more or null

    All possible effort levels.

    • "low"

    • "medium"

    • "high"

    • "xhigh"

    • "max"

Beta Text Block

• BetaTextBlock object

  • type: "text"

    default: text

  • citations: array of BetaTextCitation or null

    Citations supporting the text block.

    The type of citation returned will depend on the type of document being cited. Citing a PDF results in page_location, plain text results in char_location, and content document results in content_block_location.

    • BetaCitationCharLocation object

      • type: "char_location"

        default: char_location

      • cited_text: string

      • document_index: number

        minimum: 0

      • document_title: string or null

      • end_char_index: number

      • file_id: string or null

      • start_char_index: number

        minimum: 0

    • BetaCitationPageLocation object

      • type: "page_location"

        default: page_location

      • cited_text: string

      • document_index: number

        minimum: 0

      • document_title: string or null

      • end_page_number: number

      • file_id: string or null

      • start_page_number: number

        minimum: 1

    • BetaCitationContentBlockLocation object

      • type: "content_block_location"

        default: content_block_location

      • cited_text: string

        The full text of the cited block range, concatenated.

        Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      • document_index: number

        minimum: 0

      • document_title: string or null

      • end_block_index: number

        Exclusive 0-based end index of the cited block range in the source's content array.

        Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

      • file_id: string or null

      • start_block_index: number

        0-based index of the first cited block in the source's content array.

        minimum: 0

    • BetaCitationsWebSearchResultLocation object

      • type: "web_search_result_location"

        default: web_search_result_location

      • cited_text: string

      • encrypted_index: string

      • title: string or null

        maxLength: 512

      • url: string

    • BetaCitationSearchResultLocation object

      • type: "search_result_location"

        default: search_result_location

      • cited_text: string

        The full text of the cited block range, concatenated.

        Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      • end_block_index: number

        Exclusive 0-based end index of the cited block range in the source's content array.

        Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

      • search_result_index: number

        0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

        Counted separately from document_index; server-side web search results are not included in this count.

        minimum: 0

      • source: string

      • start_block_index: number

        0-based index of the first cited block in the source's content array.

        minimum: 0

      • title: string or null

  • text: string

    minLength: 0

Beta Text Block Param

• BetaTextBlockParam object

  • type: "text"

  • text: string

    minLength: 1

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • citations: optional array of BetaTextCitationParam or null

    • BetaCitationCharLocationParam object

      • type: "char_location"

      • cited_text: string

      • document_index: number

        minimum: 0

      • document_title: string or null

        maxLength: 500, minLength: 1

      • end_char_index: number

      • start_char_index: number

        minimum: 0

    • BetaCitationPageLocationParam object

      • type: "page_location"

      • cited_text: string

      • document_index: number

        minimum: 0

      • document_title: string or null

        maxLength: 500, minLength: 1

      • end_page_number: number

      • start_page_number: number

        minimum: 1

    • BetaCitationContentBlockLocationParam object

      • type: "content_block_location"

      • cited_text: string

        The full text of the cited block range, concatenated.

        Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      • document_index: number

        minimum: 0

      • document_title: string or null

        maxLength: 500, minLength: 1

      • end_block_index: number

        Exclusive 0-based end index of the cited block range in the source's content array.

        Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

      • start_block_index: number

        0-based index of the first cited block in the source's content array.

        minimum: 0

    • BetaCitationWebSearchResultLocationParam object

      • type: "web_search_result_location"

      • cited_text: string

      • encrypted_index: string

      • title: string or null

        maxLength: 512, minLength: 1

      • url: string

        minLength: 1

    • BetaCitationSearchResultLocationParam object

      • type: "search_result_location"

      • cited_text: string

        The full text of the cited block range, concatenated.

        Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      • end_block_index: number

        Exclusive 0-based end index of the cited block range in the source's content array.

        Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

      • search_result_index: number

        0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

        Counted separately from document_index; server-side web search results are not included in this count.

        minimum: 0

      • source: string

      • start_block_index: number

        0-based index of the first cited block in the source's content array.

        minimum: 0

      • title: string or null

Beta Text Citation

• BetaTextCitation = BetaCitationCharLocation or BetaCitationPageLocation or BetaCitationContentBlockLocation or 2 more

  • BetaCitationCharLocation object

    • type: "char_location"

      default: char_location

    • cited_text: string

    • document_index: number

      minimum: 0

    • document_title: string or null

    • end_char_index: number

    • file_id: string or null

    • start_char_index: number

      minimum: 0

  • BetaCitationPageLocation object

    • type: "page_location"

      default: page_location

    • cited_text: string

    • document_index: number

      minimum: 0

    • document_title: string or null

    • end_page_number: number

    • file_id: string or null

    • start_page_number: number

      minimum: 1

  • BetaCitationContentBlockLocation object

    • type: "content_block_location"

      default: content_block_location

    • cited_text: string

      The full text of the cited block range, concatenated.

      Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

    • document_index: number

      minimum: 0

    • document_title: string or null

    • end_block_index: number

      Exclusive 0-based end index of the cited block range in the source's content array.

      Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

    • file_id: string or null

    • start_block_index: number

      0-based index of the first cited block in the source's content array.

      minimum: 0

  • BetaCitationsWebSearchResultLocation object

    • type: "web_search_result_location"

      default: web_search_result_location

    • cited_text: string

    • encrypted_index: string

    • title: string or null

      maxLength: 512

    • url: string

  • BetaCitationSearchResultLocation object

    • type: "search_result_location"

      default: search_result_location

    • cited_text: string

      The full text of the cited block range, concatenated.

      Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

    • end_block_index: number

      Exclusive 0-based end index of the cited block range in the source's content array.

      Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

    • search_result_index: number

      0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

      Counted separately from document_index; server-side web search results are not included in this count.

      minimum: 0

    • source: string

    • start_block_index: number

      0-based index of the first cited block in the source's content array.

      minimum: 0

    • title: string or null

Beta Text Citation Param

• BetaTextCitationParam = BetaCitationCharLocationParam or BetaCitationPageLocationParam or BetaCitationContentBlockLocationParam or 2 more

  • BetaCitationCharLocationParam object

    • type: "char_location"

    • cited_text: string

    • document_index: number

      minimum: 0

    • document_title: string or null

      maxLength: 500, minLength: 1

    • end_char_index: number

    • start_char_index: number

      minimum: 0

  • BetaCitationPageLocationParam object

    • type: "page_location"

    • cited_text: string

    • document_index: number

      minimum: 0

    • document_title: string or null

      maxLength: 500, minLength: 1

    • end_page_number: number

    • start_page_number: number

      minimum: 1

  • BetaCitationContentBlockLocationParam object

    • type: "content_block_location"

    • cited_text: string

      The full text of the cited block range, concatenated.

      Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

    • document_index: number

      minimum: 0

    • document_title: string or null

      maxLength: 500, minLength: 1

    • end_block_index: number

      Exclusive 0-based end index of the cited block range in the source's content array.

      Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

    • start_block_index: number

      0-based index of the first cited block in the source's content array.

      minimum: 0

  • BetaCitationWebSearchResultLocationParam object

    • type: "web_search_result_location"

    • cited_text: string

    • encrypted_index: string

    • title: string or null

      maxLength: 512, minLength: 1

    • url: string

      minLength: 1

  • BetaCitationSearchResultLocationParam object

    • type: "search_result_location"

    • cited_text: string

      The full text of the cited block range, concatenated.

      Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

    • end_block_index: number

      Exclusive 0-based end index of the cited block range in the source's content array.

      Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

    • search_result_index: number

      0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

      Counted separately from document_index; server-side web search results are not included in this count.

      minimum: 0

    • source: string

    • start_block_index: number

      0-based index of the first cited block in the source's content array.

      minimum: 0

    • title: string or null

Beta Text Delta

• BetaTextDelta object

  • type: "text_delta"

    default: text_delta

  • text: string

Beta Text Editor Code Execution Create Result Block

• BetaTextEditorCodeExecutionCreateResultBlock object

  • type: "text_editor_code_execution_create_result"

    default: text_editor_code_execution_create_result

  • is_file_update: boolean

Beta Text Editor Code Execution Create Result Block Param

• BetaTextEditorCodeExecutionCreateResultBlockParam object

  • type: "text_editor_code_execution_create_result"

  • is_file_update: boolean

Beta Text Editor Code Execution Str Replace Result Block

• BetaTextEditorCodeExecutionStrReplaceResultBlock object

  • type: "text_editor_code_execution_str_replace_result"

    default: text_editor_code_execution_str_replace_result

  • lines: array of string or null

  • new_lines: number or null

  • new_start: number or null

  • old_lines: number or null

  • old_start: number or null

Beta Text Editor Code Execution Str Replace Result Block Param

• BetaTextEditorCodeExecutionStrReplaceResultBlockParam object

  • type: "text_editor_code_execution_str_replace_result"

  • lines: optional array of string or null

  • new_lines: optional number or null

  • new_start: optional number or null

  • old_lines: optional number or null

  • old_start: optional number or null

Beta Text Editor Code Execution Tool Result Block

• BetaTextEditorCodeExecutionToolResultBlock object

  • type: "text_editor_code_execution_tool_result"

    default: text_editor_code_execution_tool_result

  • content: BetaTextEditorCodeExecutionToolResultError or BetaTextEditorCodeExecutionViewResultBlock or BetaTextEditorCodeExecutionCreateResultBlock or BetaTextEditorCodeExecutionStrReplaceResultBlock

    • BetaTextEditorCodeExecutionToolResultError object

      • type: "text_editor_code_execution_tool_result_error"

        default: text_editor_code_execution_tool_result_error

      • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

        • "invalid_tool_input"

        • "unavailable"

        • "too_many_requests"

        • "execution_time_exceeded"

        • "file_not_found"

      • error_message: string or null

    • BetaTextEditorCodeExecutionViewResultBlock object

      • type: "text_editor_code_execution_view_result"

        default: text_editor_code_execution_view_result

      • content: string

      • file_type: "text" or "image" or "pdf"

        • "text"

        • "image"

        • "pdf"

      • num_lines: number or null

      • start_line: number or null

      • total_lines: number or null

    • BetaTextEditorCodeExecutionCreateResultBlock object

      • type: "text_editor_code_execution_create_result"

        default: text_editor_code_execution_create_result

      • is_file_update: boolean

    • BetaTextEditorCodeExecutionStrReplaceResultBlock object

      • type: "text_editor_code_execution_str_replace_result"

        default: text_editor_code_execution_str_replace_result

      • lines: array of string or null

      • new_lines: number or null

      • new_start: number or null

      • old_lines: number or null

      • old_start: number or null

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Text Editor Code Execution Tool Result Block Param

• BetaTextEditorCodeExecutionToolResultBlockParam object

  • type: "text_editor_code_execution_tool_result"

  • content: BetaTextEditorCodeExecutionToolResultErrorParam or BetaTextEditorCodeExecutionViewResultBlockParam or BetaTextEditorCodeExecutionCreateResultBlockParam or BetaTextEditorCodeExecutionStrReplaceResultBlockParam

    • BetaTextEditorCodeExecutionToolResultErrorParam object

      • type: "text_editor_code_execution_tool_result_error"

      • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

        • "invalid_tool_input"

        • "unavailable"

        • "too_many_requests"

        • "execution_time_exceeded"

        • "file_not_found"

      • error_message: optional string or null

    • BetaTextEditorCodeExecutionViewResultBlockParam object

      • type: "text_editor_code_execution_view_result"

      • content: string

      • file_type: "text" or "image" or "pdf"

        • "text"

        • "image"

        • "pdf"

      • num_lines: optional number or null

      • start_line: optional number or null

      • total_lines: optional number or null

    • BetaTextEditorCodeExecutionCreateResultBlockParam object

      • type: "text_editor_code_execution_create_result"

      • is_file_update: boolean

    • BetaTextEditorCodeExecutionStrReplaceResultBlockParam object

      • type: "text_editor_code_execution_str_replace_result"

      • lines: optional array of string or null

      • new_lines: optional number or null

      • new_start: optional number or null

      • old_lines: optional number or null

      • old_start: optional number or null

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta Text Editor Code Execution Tool Result Error

• BetaTextEditorCodeExecutionToolResultError object

  • type: "text_editor_code_execution_tool_result_error"

    default: text_editor_code_execution_tool_result_error

  • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

    • "invalid_tool_input"

    • "unavailable"

    • "too_many_requests"

    • "execution_time_exceeded"

    • "file_not_found"

  • error_message: string or null

Beta Text Editor Code Execution Tool Result Error Param

• BetaTextEditorCodeExecutionToolResultErrorParam object

  • type: "text_editor_code_execution_tool_result_error"

  • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

    • "invalid_tool_input"

    • "unavailable"

    • "too_many_requests"

    • "execution_time_exceeded"

    • "file_not_found"

  • error_message: optional string or null

Beta Text Editor Code Execution View Result Block

• BetaTextEditorCodeExecutionViewResultBlock object

  • type: "text_editor_code_execution_view_result"

    default: text_editor_code_execution_view_result

  • content: string

  • file_type: "text" or "image" or "pdf"

    • "text"

    • "image"

    • "pdf"

  • num_lines: number or null

  • start_line: number or null

  • total_lines: number or null

Beta Text Editor Code Execution View Result Block Param

• BetaTextEditorCodeExecutionViewResultBlockParam object

  • type: "text_editor_code_execution_view_result"

  • content: string

  • file_type: "text" or "image" or "pdf"

    • "text"

    • "image"

    • "pdf"

  • num_lines: optional number or null

  • start_line: optional number or null

  • total_lines: optional number or null

Beta Thinking Block

• BetaThinkingBlock object

  • type: "thinking"

    default: thinking

  • signature: string

    A value used to verify that this thinking block was generated by Claude when it is passed back to the API.

    This is an opaque field and should not be interpreted or parsed. When passing thinking blocks back to the API (required when using tools with extended thinking), pass them back exactly as received, with this field intact.

    See extended thinking for details.

  • thinking: string

    The text of Claude's thinking process for this block.

Beta Thinking Block Binding

• BetaThinkingBlockBinding object

  Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

  • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

    What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

    • "error"

    • "drop_block"

Beta Thinking Block Param

• BetaThinkingBlockParam object

  • type: "thinking"

  • signature: string

    The signature value of this thinking block, exactly as returned by the API in a previous response. Used to verify that the block was generated by Claude.

    Thinking blocks must be passed back unmodified and in their original order; a modified block results in a 400 invalid_request_error.

  • thinking: string

    The thinking text of this block as returned by the API.

Beta Thinking Config Adaptive

• BetaThinkingConfigAdaptive object

  • type: "adaptive"

  • block_binding: optional BetaThinkingBlockBinding or null

    Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

    • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

      What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

      • "error"

      • "drop_block"

  • display: optional "summarized" or "omitted" or "updates" or null

    Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

    • "summarized"

    • "omitted"

    • "updates"

Beta Thinking Config Disabled

• BetaThinkingConfigDisabled object

  • type: "disabled"

Beta Thinking Config Enabled

• BetaThinkingConfigEnabled object

  • type: "enabled"

  • budget_tokens: number

    Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

    Must be ≥1024 and less than max_tokens.

    See extended thinking for details.

    minimum: 1024

  • block_binding: optional BetaThinkingBlockBinding or null

    Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

    • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

      What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

      • "error"

      • "drop_block"

  • display: optional "summarized" or "omitted" or "updates" or null

    Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

    • "summarized"

    • "omitted"

    • "updates"

Beta Thinking Config Param

• BetaThinkingConfigParam = BetaThinkingConfigEnabled or BetaThinkingConfigDisabled or BetaThinkingConfigAdaptive

  Configuration for enabling Claude's extended thinking.

  When enabled, responses include thinking content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your max_tokens limit.

  See extended thinking for details.

  • BetaThinkingConfigEnabled object

    • type: "enabled"

    • budget_tokens: number

      Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

      Must be ≥1024 and less than max_tokens.

      See extended thinking for details.

      minimum: 1024

    • block_binding: optional BetaThinkingBlockBinding or null

      Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

      • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

        What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

        • "error"

        • "drop_block"

    • display: optional "summarized" or "omitted" or "updates" or null

      Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

      • "summarized"

      • "omitted"

      • "updates"

  • BetaThinkingConfigDisabled object

    • type: "disabled"

  • BetaThinkingConfigAdaptive object

    • type: "adaptive"

    • block_binding: optional BetaThinkingBlockBinding or null

      Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

    • display: optional "summarized" or "omitted" or "updates" or null

      Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

      • "summarized"

      • "omitted"

      • "updates"

Beta Thinking Delta

• BetaThinkingDelta object

  • type: "thinking_delta"

    default: thinking_delta

  • estimated_tokens: number or null

    Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the thinking-token-count-2026-05-13 beta is set; null unless thinking.display resolves to "omitted" and a count is due this frame. Sum the increments across thinking_delta frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; usage.output_tokens remains authoritative.

  • thinking: string

    The incremental thinking text for this content block. Concatenate the thinking values of successive thinking_delta events to assemble the block's full thinking value.

Beta Thinking Dropped Input Transformation

• BetaThinkingDroppedInputTransformation object

  • type: "thinking_dropped"

    Always thinking_dropped for this entry type.

    default: thinking_dropped

  • path: string

    Where the removed block was in your request, as messages.\{i\}.content.\{j\}: i indexes the messages array you sent and j that message's content array — the same form error messages use.

  • reason: "model_binding_mismatch" or "prefix_binding_mismatch" or "organization_binding_mismatch" or "end_user_binding_mismatch"

    Which binding check removed the block: model_binding_mismatch — it was created by a model whose reasoning the requested model may not read; prefix_binding_mismatch — the conversation before it differs from the conversation it was created in (the rest of that turn's consecutive thinking blocks are removed with it, each with this reason); organization_binding_mismatch — it was created under a different organization (an Anthropic organization, AWS account or Google Cloud project) and this organization is not one of its additional organizations; end_user_binding_mismatch — it was created for a different end user, or was removed by the consumer-organization binding. A block that would fail several checks reports one reason, in this order of precedence: organization_binding_mismatch, end_user_binding_mismatch, model_binding_mismatch, prefix_binding_mismatch.

    • "model_binding_mismatch"

    • "prefix_binding_mismatch"

    • "organization_binding_mismatch"

    • "end_user_binding_mismatch"

Beta Thinking Prefix Mismatch Behavior

• BetaThinkingPrefixMismatchBehavior = "error" or "drop_block"

  What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

  • "error"

  • "drop_block"

Beta Thinking Turns

• BetaThinkingTurns object

  • type: "thinking_turns"

  • value: number

    minimum: 1

Beta Token Task Budget

• BetaTokenTaskBudget object

  User-configurable total token budget across contexts.

  • type: "tokens"

    The budget type. Currently only 'tokens' is supported.

  • total: number

    Total token budget across all contexts in the session.

    minimum: 1024

  • remaining: optional number or null

    Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

    minimum: 0

Beta Tool

• BetaTool object

  • type: optional "custom" or null

  • input_schema: object

    JSON schema for this tool's input.

    This defines the shape of the input that your tool accepts and that the model will produce.

    • type: "object"

    • properties: optional map[unknown] or null

    • required: optional array of string or null

  • name: string

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

    maxLength: 128, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,128}$

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • description: optional string

    Description of what this tool does.

    Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

  • eager_input_streaming: optional boolean or null

    Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Bash 20241022

• BetaToolBash20241022 object

  • type: "bash_20241022"

  • name: "bash"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Bash 20250124

• BetaToolBash20250124 object

  • type: "bash_20250124"

  • name: "bash"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Change MCP Tool Reference

• BetaToolChangeMCPToolReference object

  Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

  • type: "mcp_tool_reference"

  • name: string

  • server_name: string

Beta Tool Change MCP Toolset Reference

• BetaToolChangeMCPToolsetReference object

  Reference to every tool in the named MCP server's toolset.

  • type: "mcp_toolset_reference"

  • server_name: string

Beta Tool Change Tool Reference

• BetaToolChangeToolReference object

  Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

  • type: "tool_reference"

  • name: string

    pattern: ^[a-zA-Z0-9_-]{1,128}$

Beta Tool Choice

• BetaToolChoice = BetaToolChoiceAuto or BetaToolChoiceAny or BetaToolChoiceTool or BetaToolChoiceNone

  How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

  • BetaToolChoiceAuto object

    The model will automatically decide whether to use tools.

    • type: "auto"

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output at most one tool use.

  • BetaToolChoiceAny object

    The model will use any available tools.

    • type: "any"

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output exactly one tool use.

  • BetaToolChoiceTool object

    The model will use the specified tool with tool_choice.name.

    • type: "tool"

    • name: string

      The name of the tool to use.

    • disable_parallel_tool_use: optional boolean

      Whether to disable parallel tool use.

      Defaults to false. If set to true, the model will output exactly one tool use.

  • BetaToolChoiceNone object

    The model will not be allowed to use tools.

    • type: "none"

Beta Tool Choice Any

• BetaToolChoiceAny object

  The model will use any available tools.

  • type: "any"

  • disable_parallel_tool_use: optional boolean

    Whether to disable parallel tool use.

    Defaults to false. If set to true, the model will output exactly one tool use.

Beta Tool Choice Auto

• BetaToolChoiceAuto object

  The model will automatically decide whether to use tools.

  • type: "auto"

  • disable_parallel_tool_use: optional boolean

    Whether to disable parallel tool use.

    Defaults to false. If set to true, the model will output at most one tool use.

Beta Tool Choice None

• BetaToolChoiceNone object

  The model will not be allowed to use tools.

  • type: "none"

Beta Tool Choice Tool

• BetaToolChoiceTool object

  The model will use the specified tool with tool_choice.name.

  • type: "tool"

  • name: string

    The name of the tool to use.

  • disable_parallel_tool_use: optional boolean

    Whether to disable parallel tool use.

    Defaults to false. If set to true, the model will output exactly one tool use.

Beta Tool Computer Use 20241022

• BetaToolComputerUse20241022 object

  • type: "computer_20241022"

  • display_height_px: number

    The height of the display in pixels.

    minimum: 1

  • display_width_px: number

    The width of the display in pixels.

    minimum: 1

  • name: "computer"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • display_number: optional number or null

    The X11 display number (e.g. 0, 1) for the display.

    minimum: 0

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Computer Use 20250124

• BetaToolComputerUse20250124 object

  • type: "computer_20250124"

  • display_height_px: number

    The height of the display in pixels.

    minimum: 1

  • display_width_px: number

    The width of the display in pixels.

    minimum: 1

  • name: "computer"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • display_number: optional number or null

    The X11 display number (e.g. 0, 1) for the display.

    minimum: 0

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Computer Use 20251124

• BetaToolComputerUse20251124 object

  • type: "computer_20251124"

  • display_height_px: number

    The height of the display in pixels.

    minimum: 1

  • display_width_px: number

    The width of the display in pixels.

    minimum: 1

  • name: "computer"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • display_number: optional number or null

    The X11 display number (e.g. 0, 1) for the display.

    minimum: 0

  • enable_zoom: optional boolean

    Whether to enable an action to take a zoomed-in screenshot of the screen.

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Reference Block

• BetaToolReferenceBlock object

  • type: "tool_reference"

    default: tool_reference

  • tool_name: string

    maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

Beta Tool Reference Block Param

• BetaToolReferenceBlockParam object

  Tool reference block that can be included in tool_result content.

  • type: "tool_reference"

  • tool_name: string

    maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

Beta Tool Result Block Param

• BetaToolResultBlockParam object

  • type: "tool_result"

  • tool_use_id: string

    pattern: ^[a-zA-Z0-9_-]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • content: optional string or array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

    • string

    • array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

      • BetaTextBlockParam object

        • type: "text"

        • text: string

          minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional array of BetaTextCitationParam or null

          • BetaCitationCharLocationParam object

            • type: "char_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_char_index: number

            • start_char_index: number

              minimum: 0

          • BetaCitationPageLocationParam object

            • type: "page_location"

            • cited_text: string

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_page_number: number

            • start_page_number: number

              minimum: 1

          • BetaCitationContentBlockLocationParam object

            • type: "content_block_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • document_index: number

              minimum: 0

            • document_title: string or null

              maxLength: 500, minLength: 1

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

          • BetaCitationWebSearchResultLocationParam object

            • type: "web_search_result_location"

            • cited_text: string

            • encrypted_index: string

            • title: string or null

              maxLength: 512, minLength: 1

            • url: string

              minLength: 1

          • BetaCitationSearchResultLocationParam object

            • type: "search_result_location"

            • cited_text: string

              The full text of the cited block range, concatenated.

              Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            • end_block_index: number

              Exclusive 0-based end index of the cited block range in the source's content array.

              Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

            • search_result_index: number

              0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from document_index; server-side web search results are not included in this count.

              minimum: 0

            • source: string

            • start_block_index: number

              0-based index of the first cited block in the source's content array.

              minimum: 0

            • title: string or null

      • BetaImageBlockParam object

        • type: "image"

        • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

          • BetaBase64ImageSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

              • "image/jpeg"

              • "image/png"

              • "image/gif"

              • "image/webp"

          • BetaURLImageSource object

            • type: "url"

            • url: string

          • BetaFileImageSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • transformations: optional BetaImageTransformationsParam or null

          Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

          • oversized_image: optional "downsize" or "error"

            What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

            • "downsize"

            • "error"

      • BetaSearchResultBlockParam object

        • type: "search_result"

        • content: array of BetaTextBlockParam

          • type: "text"

          • text: string

            minLength: 1

          • cache_control: optional BetaCacheControlEphemeral or null

            Create a cache control breakpoint at this content block.

          • citations: optional array of BetaTextCitationParam or null

        • source: string

        • title: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam

          • enabled: optional boolean

      • BetaRequestDocumentBlock object

        • type: "document"

        • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

          • BetaBase64PDFSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "application/pdf"

          • BetaPlainTextSource object

            • type: "text"

            • data: string

            • media_type: "text/plain"

          • BetaContentBlockSource object

            • type: "content"

            • content: string or array of BetaContentBlockSourceContent

              • string

              • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

                • BetaTextBlockParam object

                • BetaImageBlockParam object

          • BetaURLPDFSource object

            • type: "url"

            • url: string

          • BetaFileDocumentSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

        • context: optional string or null

          minLength: 1

        • title: optional string or null

          maxLength: 500, minLength: 1

      • BetaToolReferenceBlockParam object

        Tool reference block that can be included in tool_result content.

        • type: "tool_reference"

        • tool_name: string

          maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

      • BetaBrowserStateBlockParam object

        The caller's browser state after a browser toolset member call — the full inventory of open tabs, which tab is active, and any side effects (tabs opened, download state changes) the call produced.

        At most one per tool_result, only on a non-error result answering a browser toolset member tool_use. The server renders the model-visible text from it; the model never sees the raw fields.

        • type: "browser_state"

        • tabs: array of BetaBrowserStateTabEntry

          All tabs open in the browser after this call — the full inventory, not a delta. May be empty. Whenever non-empty, exactly one entry carries active: true.

          maxItems: 100

          • tab_id: string

            The caller-assigned identifier for this tab, unique within the inventory.

            maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

          • title: string

            The title of the page the tab is showing. May be empty.

            maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

          • url: string

            The URL of the page the tab is showing. May be empty.

            maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

          • active: optional boolean

            Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • state_changes: optional array of BetaBrowserStateChange or null

          Tabs opened and download state changes during this call. "Nothing to report" is expressed by omitting the field, never by an empty list.

          maxItems: 200, minItems: 1

          • BetaBrowserStateChangeTabOpened object

            A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

            Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

            • type: "tab_opened"

            • tab_id: string

              The tab_id of the opened tab, present in tabs.

              maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

          • BetaBrowserStateChangeDownloadStarted object

            A file download that started during this call.

            • type: "download_started"

            • download_id: string

              The caller-assigned identifier for this download, stable across the state changes reporting it.

              maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • url: string

              The final post-redirect URL the download was served from.

              maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

          • BetaBrowserStateChangeDownloadCompleted object

            A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

            • type: "download_completed"

            • download_id: string

              The caller-assigned identifier for this download, stable across the state changes reporting it.

              maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • url: string

              The final post-redirect URL the download was served from.

              maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • path: optional string or null

              Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

              pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

            • size_bytes: optional number or null

              The completed download's size.

              minimum: 0

          • BetaBrowserStateChangeDownloadFailed object

            A file download that failed — or was cancelled — during this call.

            • type: "download_failed"

            • download_id: string

              The caller-assigned identifier for this download, stable across the state changes reporting it.

              maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • url: string

              The final post-redirect URL the download was served from.

              maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

            • error: optional string or null

              The failure or cancellation detail, when known.

              pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

  • is_error: optional boolean

  • toolset_name: optional string or null

    For a toolset member tool_result, the toolset family of the paired tool_use.

    maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

Beta Tool Search Tool Bm25 20251119

• BetaToolSearchToolBm25_20251119 object

  • type: "tool_search_tool_bm25_20251119" or "tool_search_tool_bm25"

    • "tool_search_tool_bm25_20251119"

    • "tool_search_tool_bm25"

  • name: "tool_search_tool_bm25"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Search Tool Regex 20251119

• BetaToolSearchToolRegex20251119 object

  • type: "tool_search_tool_regex_20251119" or "tool_search_tool_regex"

    • "tool_search_tool_regex_20251119"

    • "tool_search_tool_regex"

  • name: "tool_search_tool_regex"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Search Tool Result Block

• BetaToolSearchToolResultBlock object

  • type: "tool_search_tool_result"

    default: tool_search_tool_result

  • content: BetaToolSearchToolResultError or BetaToolSearchToolSearchResultBlock

    • BetaToolSearchToolResultError object

      • type: "tool_search_tool_result_error"

        default: tool_search_tool_result_error

      • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

        • "invalid_tool_input"

        • "unavailable"

        • "too_many_requests"

        • "execution_time_exceeded"

      • error_message: string or null

    • BetaToolSearchToolSearchResultBlock object

      • type: "tool_search_tool_search_result"

        default: tool_search_tool_search_result

      • tool_references: array of BetaToolReferenceBlock

        • type: "tool_reference"

          default: tool_reference

        • tool_name: string

          maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Tool Search Tool Result Block Param

• BetaToolSearchToolResultBlockParam object

  • type: "tool_search_tool_result"

  • content: BetaToolSearchToolResultErrorParam or BetaToolSearchToolSearchResultBlockParam

    • BetaToolSearchToolResultErrorParam object

      • type: "tool_search_tool_result_error"

      • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

        • "invalid_tool_input"

        • "unavailable"

        • "too_many_requests"

        • "execution_time_exceeded"

      • error_message: optional string or null

    • BetaToolSearchToolSearchResultBlockParam object

      • type: "tool_search_tool_search_result"

      • tool_references: array of BetaToolReferenceBlockParam

        • type: "tool_reference"

        • tool_name: string

          maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

          • type: "ephemeral"

          • ttl: optional "5m" or "1h"

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            • 5m: 5 minutes
            • 1h: 1 hour

            Defaults to 5m. See prompt caching pricing for details.

            • "5m"

            • "1h"

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

Beta Tool Search Tool Result Error

• BetaToolSearchToolResultError object

  • type: "tool_search_tool_result_error"

    default: tool_search_tool_result_error

  • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

    • "invalid_tool_input"

    • "unavailable"

    • "too_many_requests"

    • "execution_time_exceeded"

  • error_message: string or null

Beta Tool Search Tool Result Error Param

• BetaToolSearchToolResultErrorParam object

  • type: "tool_search_tool_result_error"

  • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

    • "invalid_tool_input"

    • "unavailable"

    • "too_many_requests"

    • "execution_time_exceeded"

  • error_message: optional string or null

Beta Tool Search Tool Search Result Block

• BetaToolSearchToolSearchResultBlock object

  • type: "tool_search_tool_search_result"

    default: tool_search_tool_search_result

  • tool_references: array of BetaToolReferenceBlock

    • type: "tool_reference"

      default: tool_reference

    • tool_name: string

      maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

Beta Tool Search Tool Search Result Block Param

• BetaToolSearchToolSearchResultBlockParam object

  • type: "tool_search_tool_search_result"

  • tool_references: array of BetaToolReferenceBlockParam

    • type: "tool_reference"

    • tool_name: string

      maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

      • type: "ephemeral"

      • ttl: optional "5m" or "1h"

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        • 5m: 5 minutes
        • 1h: 1 hour

        Defaults to 5m. See prompt caching pricing for details.

        • "5m"

        • "1h"

Beta Tool Text Editor 20241022

• BetaToolTextEditor20241022 object

  • type: "text_editor_20241022"

  • name: "str_replace_editor"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Text Editor 20250124

• BetaToolTextEditor20250124 object

  • type: "text_editor_20250124"

  • name: "str_replace_editor"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Text Editor 20250429

• BetaToolTextEditor20250429 object

  • type: "text_editor_20250429"

  • name: "str_replace_based_edit_tool"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • input_examples: optional array of map[unknown]

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Text Editor 20250728

• BetaToolTextEditor20250728 object

  • type: "text_editor_20250728"

  • name: "str_replace_based_edit_tool"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • input_examples: optional array of map[unknown]

  • max_characters: optional number or null

    Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

    minimum: 1

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Tool Union

• BetaToolUnion = BetaTool or BetaToolBash20241022 or BetaToolBash20250124 or 25 more

  Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

  • BetaTool object

    • type: optional "custom" or null

    • input_schema: object

      JSON schema for this tool's input.

      This defines the shape of the input that your tool accepts and that the model will produce.

      • type: "object"

      • properties: optional map[unknown] or null

      • required: optional array of string or null

    • name: string

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

      maxLength: 128, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,128}$

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

      • type: "ephemeral"

      • ttl: optional "5m" or "1h"

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        • 5m: 5 minutes
        • 1h: 1 hour

        Defaults to 5m. See prompt caching pricing for details.

        • "5m"

        • "1h"

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • description: optional string

      Description of what this tool does.

      Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

    • eager_input_streaming: optional boolean or null

      Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolBash20241022 object

    • type: "bash_20241022"

    • name: "bash"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolBash20250124 object

    • type: "bash_20250124"

    • name: "bash"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20250522 object

    • type: "code_execution_20250522"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20250825 object

    • type: "code_execution_20250825"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20260120 object

    Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

    • type: "code_execution_20260120"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaCodeExecutionTool20260521 object

    Code execution tool with REPL state persistence.

    • type: "code_execution_20260521"

    • name: "code_execution"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaBrowserToolset20260801 object

    The browser toolset: a single tools[] entry (carrying no name) that declares the browser tool family. The model is served the family's tool with any members disabled via configs removed from its schema.

    • type: "browser_toolset_20260801"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional BetaBrowserToolsetConfigs or null

      Per-member configuration for browser_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

      • type: optional BetaBrowserTypeConfig or null

        type's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • close_tab: optional BetaBrowserCloseTabConfig or null

        close_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • double_click: optional BetaBrowserDoubleClickConfig or null

        double_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • file_upload: optional BetaBrowserFileUploadConfig or null

        file_upload's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • find: optional BetaBrowserFindConfig or null

        find's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • form_input: optional BetaBrowserFormInputConfig or null

        form_input's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • get_page_text: optional BetaBrowserGetPageTextConfig or null

        get_page_text's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hold_key: optional BetaBrowserHoldKeyConfig or null

        hold_key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hover: optional BetaBrowserHoverConfig or null

        hover's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • javascript_exec: optional BetaBrowserJavascriptExecConfig or null

        javascript_exec's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • key: optional BetaBrowserKeyConfig or null

        key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click: optional BetaBrowserLeftClickConfig or null

        left_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click_drag: optional BetaBrowserLeftClickDragConfig or null

        left_click_drag's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_down: optional BetaBrowserLeftMouseDownConfig or null

        left_mouse_down's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_up: optional BetaBrowserLeftMouseUpConfig or null

        left_mouse_up's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • list_tabs: optional BetaBrowserListTabsConfig or null

        list_tabs's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • middle_click: optional BetaBrowserMiddleClickConfig or null

        middle_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • mouse_move: optional BetaBrowserMouseMoveConfig or null

        mouse_move's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • navigate: optional BetaBrowserNavigateConfig or null

        navigate's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • new_tab: optional BetaBrowserNewTabConfig or null

        new_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_console: optional BetaBrowserReadConsoleConfig or null

        read_console's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_network: optional BetaBrowserReadNetworkConfig or null

        read_network's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • read_page: optional BetaBrowserReadPageConfig or null

        read_page's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • right_click: optional BetaBrowserRightClickConfig or null

        right_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • screenshot: optional BetaBrowserScreenshotConfig or null

        screenshot's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll: optional BetaBrowserScrollConfig or null

        scroll's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll_to: optional BetaBrowserScrollToConfig or null

        scroll_to's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • switch_tab: optional BetaBrowserSwitchTabConfig or null

        switch_tab's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • triple_click: optional BetaBrowserTripleClickConfig or null

        triple_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • wait: optional BetaBrowserWaitConfig or null

        wait's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • zoom: optional BetaBrowserZoomConfig or null

        zoom's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • BetaToolComputerUse20241022 object

    • type: "computer_20241022"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaMemoryTool20250818 object

    • type: "memory_20250818"

    • name: "memory"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolComputerUse20250124 object

    • type: "computer_20250124"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20241022 object

    • type: "text_editor_20241022"

    • name: "str_replace_editor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolComputerUse20251124 object

    • type: "computer_20251124"

    • display_height_px: number

      The height of the display in pixels.

      minimum: 1

    • display_width_px: number

      The width of the display in pixels.

      minimum: 1

    • name: "computer"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • display_number: optional number or null

      The X11 display number (e.g. 0, 1) for the display.

      minimum: 0

    • enable_zoom: optional boolean

      Whether to enable an action to take a zoomed-in screenshot of the screen.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaComputerToolset20260801 object

    The computer toolset: a single tools[] entry (carrying no name) that declares the computer tool family. The model is served the family's tool with any members disabled via configs removed from its schema. Every member is enabled by default, zoom included. The single-tool options display_number and enable_zoom are not fields of a toolset entry — it carries only type, configs, and cache_control; zoom is controlled via configs.zoom.enabled.

    • type: "computer_toolset_20260801"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional BetaComputerToolsetConfigs or null

      Per-member configuration for computer_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

      • type: optional BetaComputerTypeConfig or null

        type's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • cursor_position: optional BetaComputerCursorPositionConfig or null

        cursor_position's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • double_click: optional BetaComputerDoubleClickConfig or null

        double_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • hold_key: optional BetaComputerHoldKeyConfig or null

        hold_key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • key: optional BetaComputerKeyConfig or null

        key's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click: optional BetaComputerLeftClickConfig or null

        left_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_click_drag: optional BetaComputerLeftClickDragConfig or null

        left_click_drag's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_down: optional BetaComputerLeftMouseDownConfig or null

        left_mouse_down's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • left_mouse_up: optional BetaComputerLeftMouseUpConfig or null

        left_mouse_up's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • middle_click: optional BetaComputerMiddleClickConfig or null

        middle_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • mouse_move: optional BetaComputerMouseMoveConfig or null

        mouse_move's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • right_click: optional BetaComputerRightClickConfig or null

        right_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • screenshot: optional BetaComputerScreenshotConfig or null

        screenshot's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • scroll: optional BetaComputerScrollConfig or null

        scroll's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • triple_click: optional BetaComputerTripleClickConfig or null

        triple_click's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • wait: optional BetaComputerWaitConfig or null

        wait's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • zoom: optional BetaComputerZoomConfig or null

        zoom's config overrides.

        • defer_loading: optional boolean or null

          Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

        • enabled: optional boolean or null

          Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

  • BetaToolTextEditor20250124 object

    • type: "text_editor_20250124"

    • name: "str_replace_editor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20250429 object

    • type: "text_editor_20250429"

    • name: "str_replace_based_edit_tool"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolTextEditor20250728 object

    • type: "text_editor_20250728"

    • name: "str_replace_based_edit_tool"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • input_examples: optional array of map[unknown]

    • max_characters: optional number or null

      Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

      minimum: 1

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebSearchTool20250305 object

    • type: "web_search_20250305"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

      • type: "approximate"

      • city: optional string or null

        The city of the user.

        maxLength: 255, minLength: 1

      • country: optional string or null

        The two letter ISO country code of the user.

        maxLength: 2, minLength: 2

      • region: optional string or null

        The region of the user.

        maxLength: 255, minLength: 1

      • timezone: optional string or null

        The IANA timezone of the user.

        maxLength: 255, minLength: 1

  • BetaWebFetchTool20250910 object

    • type: "web_fetch_20250910"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

      • enabled: optional boolean

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebSearchTool20260209 object

    • type: "web_search_20260209"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

  • BetaWebFetchTool20260209 object

    • type: "web_fetch_20260209"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaWebFetchTool20260309 object

    Web fetch tool with use_cache parameter for bypassing cached content.

    • type: "web_fetch_20260309"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • use_cache: optional boolean

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  • BetaWebSearchTool20260318 object

    • type: "web_search_20260318"

    • name: "web_search"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

    • blocked_domains: optional array of string or null

      If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • response_inclusion: optional "full" or "excluded"

      How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

      • "full"

      • "excluded"

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • user_location: optional BetaUserLocation or null

      Parameters for the user's location. Used to provide more relevant search results.

  • BetaWebFetchTool20260318 object

    • type: "web_fetch_20260318"

    • name: "web_fetch"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • allowed_domains: optional array of string or null

      List of domains to allow fetching from

    • blocked_domains: optional array of string or null

      List of domains to block fetching from

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      Citations configuration for fetched documents. Citations are disabled by default.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_content_tokens: optional number or null

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

      exclusiveMinimum: 0

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • response_inclusion: optional "full" or "excluded"

      How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

      • "full"

      • "excluded"

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

    • use_cache: optional boolean

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  • BetaAdvisorTool20260301 object

    • type: "advisor_20260301"

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1"

          Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

        • "claude-mythos-5-1"

          Our most capable model for cybersecurity and biology research, available through trusted access programs

        • "claude-sonnet-5"

          High-performance model for coding and agents

        • "claude-fable-5"

          Next generation of intelligence for the hardest knowledge work and coding problems

        • "claude-mythos-5"

          Most capable model for cybersecurity and biology research

        • "claude-opus-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-8"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-7"

          Powerful intelligence for long-running agents and coding

        • "claude-mythos-preview"

          New class of intelligence, strongest in coding and cybersecurity

        • "claude-opus-4-6"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-6"

          Best combination of speed and intelligence

        • "claude-haiku-4-5"

          Fastest model with near-frontier intelligence

        • "claude-haiku-4-5-20251001"

          Fastest model with near-frontier intelligence

        • "claude-opus-4-5"

          Powerful intelligence for long-running agents and coding

        • "claude-opus-4-5-20251101"

          Powerful intelligence for long-running agents and coding

        • "claude-sonnet-4-5"

          High-performance model for agents and coding

        • "claude-sonnet-4-5-20250929"

          High-performance model for agents and coding

      • string

    • name: "advisor"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • caching: optional BetaCacheControlEphemeral or null

      Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • max_tokens: optional number or null

      Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

      minimum: 1024

    • max_uses: optional number or null

      Maximum number of times the tool can be used in the API request.

      exclusiveMinimum: 0

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolSearchToolBm25_20251119 object

    • type: "tool_search_tool_bm25_20251119" or "tool_search_tool_bm25"

      • "tool_search_tool_bm25_20251119"

      • "tool_search_tool_bm25"

    • name: "tool_search_tool_bm25"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaToolSearchToolRegex20251119 object

    • type: "tool_search_tool_regex_20251119" or "tool_search_tool_regex"

      • "tool_search_tool_regex_20251119"

      • "tool_search_tool_regex"

    • name: "tool_search_tool_regex"

      Name of the tool.

      This is how the tool will be called by the model and in tool_use blocks.

    • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

      • "direct"

      • "code_execution_20250825"

      • "code_execution_20260120"

      • "code_execution_20260521"

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • defer_loading: optional boolean

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    • strict: optional boolean

      When true, guarantees schema validation on tool names and inputs

  • BetaMCPToolset object

    Configuration for a group of tools from an MCP server.

    Allows configuring enabled status and defer_loading for all tools from an MCP server, with optional per-tool overrides.

    • type: "mcp_toolset"

    • mcp_server_name: string

      Name of the MCP server to configure tools for

      maxLength: 255, minLength: 1

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • configs: optional map[BetaMCPToolConfig] or null

      Configuration overrides for specific tools, keyed by tool name

      • defer_loading: optional boolean

      • enabled: optional boolean

    • default_config: optional BetaMCPToolDefaultConfig

      Default configuration applied to all tools from this server

      • defer_loading: optional boolean

      • enabled: optional boolean

Beta Tool Use Block

• BetaToolUseBlock object

  • type: "tool_use"

    default: tool_use

  • id: string

    pattern: ^[a-zA-Z0-9_-]+$

  • input: map[unknown]

  • name: string

    minLength: 1

  • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

    Tool invocation directly from the model.

    • BetaDirectCaller object

      Tool invocation directly from the model.

      • type: "direct"

    • BetaServerToolCaller object

      Tool invocation generated by a server-side tool.

      • type: "code_execution_20250825"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaServerToolCaller20260120 object

      • type: "code_execution_20260120"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • toolset_name: optional string or null

    For a toolset member tool_use, the toolset family.

    maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

Beta Tool Use Block Param

• BetaToolUseBlockParam object

  • type: "tool_use"

  • id: string

    pattern: ^[a-zA-Z0-9_-]+$

  • input: map[unknown]

  • name: string

    maxLength: 200, minLength: 1

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

    Tool invocation directly from the model.

    • BetaDirectCaller object

      Tool invocation directly from the model.

      • type: "direct"

    • BetaServerToolCaller object

      Tool invocation generated by a server-side tool.

      • type: "code_execution_20250825"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaServerToolCaller20260120 object

      • type: "code_execution_20260120"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • toolset_name: optional string or null

    For a toolset member tool_use, the toolset family this member belongs to.

    maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

Beta Tool Uses Keep

• BetaToolUsesKeep object

  • type: "tool_uses"

  • value: number

    minimum: 0

Beta Tool Uses Trigger

• BetaToolUsesTrigger object

  • type: "tool_uses"

  • value: number

    minimum: 1

Beta URL Image Source

• BetaURLImageSource object

  • type: "url"

  • url: string

Beta URL PDF Source

• BetaURLPDFSource object

  • type: "url"

  • url: string

Beta Usage

• BetaUsage object

  • cache_creation: BetaCacheCreation or null

    Breakdown of cached tokens by TTL

    • ephemeral_1h_input_tokens: number

      The number of input tokens used to create the 1 hour cache entry.

      default: 0, minimum: 0

    • ephemeral_5m_input_tokens: number

      The number of input tokens used to create the 5 minute cache entry.

      default: 0, minimum: 0

  • cache_creation_input_tokens: number or null

    The number of input tokens used to create the cache entry.

    minimum: 0

  • cache_read_input_tokens: number or null

    The number of input tokens read from the cache.

    minimum: 0

  • fallback_credit: BetaFallbackCreditUsage or null

    Outcome of the fallback_credit_token presented on this request.

    • status: BetaFallbackCreditRedeemed or BetaFallbackCreditNotApplied

      Whether the fallback-credit reprice was applied to this response's billing.

      A union discriminated on type. redeemed: the retry is billed as if the conversation had been on the retry model all along — including when the resulting shift is zero because there was nothing to move. not_applied: no reprice was applied; the arm's reason says why.

      • BetaFallbackCreditRedeemed object

        The reprice was applied: the retry is billed as if the conversation had been on the retry model all along.

        • type: "redeemed"

          default: redeemed

      • BetaFallbackCreditNotApplied object

        No reprice was applied; reason says why.

        • type: "not_applied"

          default: not_applied

        • reason: "body_mismatch" or "continuation_excluded" or "continuation_only" or 9 more

          Why the reprice was not applied.

          A closed enum; additions to the redemption-check vocabulary arrive as deliberate schema updates.

          • "body_mismatch"

          • "continuation_excluded"

          • "continuation_only"

          • "expired"

          • "invalid_target_model"

          • "not_enabled"

          • "reprice_unavailable"

          • "temporarily_unavailable"

          • "variant_fields_present"

          • "wrong_organization"

          • "wrong_platform"

          • "wrong_workspace"

        • remove_to_redeem: optional array of string or null

          Request fields to remove before retrying, so the retry can redeem this token.

          Present exactly when reason is variant_fields_present — never null, never an empty array; absent otherwise. Fields are named only from your own request, and only after the sealed variant hash matched. A served best-effort retry has already been billed at normal price; nothing redeems retroactively, but a corrected re-send inside the token's five-minute window can still redeem.

  • inference_geo: string or null

    The geographic region where inference was performed for this request.

  • input_tokens: number

    The number of input tokens which were used.

    minimum: 0

  • iterations: BetaIterationsUsage or null

    Per-iteration token usage breakdown.

    Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by type. For message entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:

    • Determine which iterations exceeded long context thresholds (>=200k tokens)
    • Calculate the context window size from the last message entry
    • Understand token accumulation across server-side tool use loops

    A compaction entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a compaction entry, even when it is the last entry. A compaction entry's tokens are not included in the top-level usage fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each compaction entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.

    • BetaMessageIterationUsage object

      Token usage for a sampling iteration.

      • type: "message"

        Usage for a sampling iteration

        default: message

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

      • cache_creation_input_tokens: number

        The number of input tokens used to create the cache entry.

        default: 0, minimum: 0

      • cache_read_input_tokens: number

        The number of input tokens read from the cache.

        default: 0, minimum: 0

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

        • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

          The model that will complete your prompt.

          See models for additional details and options.

          • "claude-fable-5-1"

            Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

          • "claude-mythos-5-1"

            Our most capable model for cybersecurity and biology research, available through trusted access programs

          • "claude-sonnet-5"

            High-performance model for coding and agents

          • "claude-fable-5"

            Next generation of intelligence for the hardest knowledge work and coding problems

          • "claude-mythos-5"

            Most capable model for cybersecurity and biology research

          • "claude-opus-5"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-8"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-7"

            Powerful intelligence for long-running agents and coding

          • "claude-mythos-preview"

            New class of intelligence, strongest in coding and cybersecurity

          • "claude-opus-4-6"

            Powerful intelligence for long-running agents and coding

          • "claude-sonnet-4-6"

            Best combination of speed and intelligence

          • "claude-haiku-4-5"

            Fastest model with near-frontier intelligence

          • "claude-haiku-4-5-20251001"

            Fastest model with near-frontier intelligence

          • "claude-opus-4-5"

            Powerful intelligence for long-running agents and coding

          • "claude-opus-4-5-20251101"

            Powerful intelligence for long-running agents and coding

          • "claude-sonnet-4-5"

            High-performance model for agents and coding

          • "claude-sonnet-4-5-20250929"

            High-performance model for agents and coding

        • string

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

    • BetaCompactionIterationUsage object

      Token usage for a compaction iteration.

      • type: "compaction"

        Usage for a compaction iteration

        default: compaction

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

      • cache_creation_input_tokens: number

        The number of input tokens used to create the cache entry.

        default: 0, minimum: 0

      • cache_read_input_tokens: number

        The number of input tokens read from the cache.

        default: 0, minimum: 0

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

    • BetaAdvisorMessageIterationUsage object

      Token usage for an advisor sub-inference iteration.

      • type: "advisor_message"

        Usage for an advisor sub-inference iteration

        default: advisor_message

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

      • cache_creation_input_tokens: number

        The number of input tokens used to create the cache entry.

        default: 0, minimum: 0

      • cache_read_input_tokens: number

        The number of input tokens read from the cache.

        default: 0, minimum: 0

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

    • BetaFallbackMessageIterationUsage object

      Token usage for the fallback-model attempt of a server-side fallback request.

      Produced in place of a message entry for whichever hop served the response. A declined hop produces the existing message entry. Whether a fallback model served the response is signalled by the presence of this entry in usage.iterations.

      • type: "fallback_message"

        Usage for the fallback-model attempt that served the response

        default: fallback_message

      • cache_creation: BetaCacheCreation or null

        Breakdown of cached tokens by TTL

      • cache_creation_input_tokens: number

        The number of input tokens used to create the cache entry.

        default: 0, minimum: 0

      • cache_read_input_tokens: number

        The number of input tokens read from the cache.

        default: 0, minimum: 0

      • input_tokens: number

        The number of input tokens which were used.

        minimum: 0

      • model: Model

        The model that will complete your prompt.

        See models for additional details and options.

      • output_tokens: number

        The number of output tokens which were used.

        minimum: 0

  • output_tokens: number

    The number of output tokens which were used.

    minimum: 0

  • output_tokens_details: BetaOutputTokensDetails or null

    Breakdown of output tokens by category.

    output_tokens remains the inclusive, authoritative total used for billing. This object provides a read-only decomposition for observability — for example, how many of the billed output tokens were spent on internal reasoning that may have been summarized before being returned to you.

    • thinking_tokens: number

      Number of output tokens the model generated as internal reasoning, including the thinking-block delimiter tokens.

      Reflects the raw reasoning the model produced, not the (possibly shorter) summarized thinking text returned in the response body. Computed by re-tokenizing the raw reasoning text, so it may differ from the model's exact generation count by a small number of tokens. Always ≤ output_tokens; output_tokens - thinking_tokens approximates the non-reasoning output.

      default: 0, minimum: 0

  • server_tool_use: BetaServerToolUsage or null

    The number of server tool requests.

    • web_fetch_requests: number

      The number of web fetch tool requests.

      default: 0, minimum: 0

    • web_search_requests: number

      The number of web search tool requests.

      default: 0, minimum: 0

  • service_tier: "standard" or "priority" or "batch" or null

    If the request used the priority, standard, or batch tier.

    • "standard"

    • "priority"

    • "batch"

  • speed: "standard" or "fast" or null

    Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

    • "standard"

    • "fast"

Beta User Location

• BetaUserLocation object

  • type: "approximate"

  • city: optional string or null

    The city of the user.

    maxLength: 255, minLength: 1

  • country: optional string or null

    The two letter ISO country code of the user.

    maxLength: 2, minLength: 2

  • region: optional string or null

    The region of the user.

    maxLength: 255, minLength: 1

  • timezone: optional string or null

    The IANA timezone of the user.

    maxLength: 255, minLength: 1

Beta Web Fetch Block

• BetaWebFetchBlock object

  • type: "web_fetch_result"

    default: web_fetch_result

  • content: BetaDocumentBlock

    • type: "document"

      default: document

    • citations: BetaCitationConfig or null

      Citation configuration for the document

      • enabled: boolean

        default: false

    • source: BetaBase64PDFSource or BetaPlainTextSource

      • BetaBase64PDFSource object

        • type: "base64"

        • data: string

          format: byte

        • media_type: "application/pdf"

      • BetaPlainTextSource object

        • type: "text"

        • data: string

        • media_type: "text/plain"

    • title: string or null

      The title of the document

  • retrieved_at: string or null

    ISO 8601 timestamp when the content was retrieved

  • url: string

    Fetched content URL

Beta Web Fetch Block Param

• BetaWebFetchBlockParam object

  • type: "web_fetch_result"

  • content: BetaRequestDocumentBlock

    • type: "document"

    • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

      • BetaBase64PDFSource object

        • type: "base64"

        • data: string

          format: byte

        • media_type: "application/pdf"

      • BetaPlainTextSource object

        • type: "text"

        • data: string

        • media_type: "text/plain"

      • BetaContentBlockSource object

        • type: "content"

        • content: string or array of BetaContentBlockSourceContent

          • string

          • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

            • BetaTextBlockParam object

              • type: "text"

              • text: string

                minLength: 1

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

                • type: "ephemeral"

                • ttl: optional "5m" or "1h"

                  The time-to-live for the cache control breakpoint.

                  This may be one the following values:

                  • 5m: 5 minutes
                  • 1h: 1 hour

                  Defaults to 5m. See prompt caching pricing for details.

                  • "5m"

                  • "1h"

              • citations: optional array of BetaTextCitationParam or null

                • BetaCitationCharLocationParam object

                  • type: "char_location"

                  • cited_text: string

                  • document_index: number

                    minimum: 0

                  • document_title: string or null

                    maxLength: 500, minLength: 1

                  • end_char_index: number

                  • start_char_index: number

                    minimum: 0

                • BetaCitationPageLocationParam object

                  • type: "page_location"

                  • cited_text: string

                  • document_index: number

                    minimum: 0

                  • document_title: string or null

                    maxLength: 500, minLength: 1

                  • end_page_number: number

                  • start_page_number: number

                    minimum: 1

                • BetaCitationContentBlockLocationParam object

                  • type: "content_block_location"

                  • cited_text: string

                    The full text of the cited block range, concatenated.

                    Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                  • document_index: number

                    minimum: 0

                  • document_title: string or null

                    maxLength: 500, minLength: 1

                  • end_block_index: number

                    Exclusive 0-based end index of the cited block range in the source's content array.

                    Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

                  • start_block_index: number

                    0-based index of the first cited block in the source's content array.

                    minimum: 0

                • BetaCitationWebSearchResultLocationParam object

                  • type: "web_search_result_location"

                  • cited_text: string

                  • encrypted_index: string

                  • title: string or null

                    maxLength: 512, minLength: 1

                  • url: string

                    minLength: 1

                • BetaCitationSearchResultLocationParam object

                  • type: "search_result_location"

                  • cited_text: string

                    The full text of the cited block range, concatenated.

                    Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                  • end_block_index: number

                    Exclusive 0-based end index of the cited block range in the source's content array.

                    Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

                  • search_result_index: number

                    0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

                    Counted separately from document_index; server-side web search results are not included in this count.

                    minimum: 0

                  • source: string

                  • start_block_index: number

                    0-based index of the first cited block in the source's content array.

                    minimum: 0

                  • title: string or null

            • BetaImageBlockParam object

              • type: "image"

              • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

                • BetaBase64ImageSource object

                  • type: "base64"

                  • data: string

                    format: byte

                  • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

                    • "image/jpeg"

                    • "image/png"

                    • "image/gif"

                    • "image/webp"

                • BetaURLImageSource object

                  • type: "url"

                  • url: string

                • BetaFileImageSource object

                  • type: "file"

                  • file_id: string

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

              • transformations: optional BetaImageTransformationsParam or null

                Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

                • oversized_image: optional "downsize" or "error"

                  What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

                  • "downsize"

                  • "error"

      • BetaURLPDFSource object

        • type: "url"

        • url: string

      • BetaFileDocumentSource object

        • type: "file"

        • file_id: string

    • cache_control: optional BetaCacheControlEphemeral or null

      Create a cache control breakpoint at this content block.

    • citations: optional BetaCitationsConfigParam or null

      • enabled: optional boolean

    • context: optional string or null

      minLength: 1

    • title: optional string or null

      maxLength: 500, minLength: 1

  • url: string

    Fetched content URL

  • retrieved_at: optional string or null

    ISO 8601 timestamp when the content was retrieved

Beta Web Fetch Tool 20250910

• BetaWebFetchTool20250910 object

  • type: "web_fetch_20250910"

  • name: "web_fetch"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • allowed_domains: optional array of string or null

    List of domains to allow fetching from

  • blocked_domains: optional array of string or null

    List of domains to block fetching from

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • citations: optional BetaCitationsConfigParam or null

    Citations configuration for fetched documents. Citations are disabled by default.

    • enabled: optional boolean

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • max_content_tokens: optional number or null

    Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    exclusiveMinimum: 0

  • max_uses: optional number or null

    Maximum number of times the tool can be used in the API request.

    exclusiveMinimum: 0

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Web Fetch Tool 20260209

• BetaWebFetchTool20260209 object

  • type: "web_fetch_20260209"

  • name: "web_fetch"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • allowed_domains: optional array of string or null

    List of domains to allow fetching from

  • blocked_domains: optional array of string or null

    List of domains to block fetching from

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • citations: optional BetaCitationsConfigParam or null

    Citations configuration for fetched documents. Citations are disabled by default.

    • enabled: optional boolean

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • max_content_tokens: optional number or null

    Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    exclusiveMinimum: 0

  • max_uses: optional number or null

    Maximum number of times the tool can be used in the API request.

    exclusiveMinimum: 0

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

Beta Web Fetch Tool 20260309

• BetaWebFetchTool20260309 object

  Web fetch tool with use_cache parameter for bypassing cached content.

  • type: "web_fetch_20260309"

  • name: "web_fetch"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • allowed_domains: optional array of string or null

    List of domains to allow fetching from

  • blocked_domains: optional array of string or null

    List of domains to block fetching from

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • citations: optional BetaCitationsConfigParam or null

    Citations configuration for fetched documents. Citations are disabled by default.

    • enabled: optional boolean

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • max_content_tokens: optional number or null

    Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    exclusiveMinimum: 0

  • max_uses: optional number or null

    Maximum number of times the tool can be used in the API request.

    exclusiveMinimum: 0

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

  • use_cache: optional boolean

    Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

Beta Web Fetch Tool 20260318

• BetaWebFetchTool20260318 object

  • type: "web_fetch_20260318"

  • name: "web_fetch"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • allowed_domains: optional array of string or null

    List of domains to allow fetching from

  • blocked_domains: optional array of string or null

    List of domains to block fetching from

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • citations: optional BetaCitationsConfigParam or null

    Citations configuration for fetched documents. Citations are disabled by default.

    • enabled: optional boolean

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • max_content_tokens: optional number or null

    Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    exclusiveMinimum: 0

  • max_uses: optional number or null

    Maximum number of times the tool can be used in the API request.

    exclusiveMinimum: 0

  • response_inclusion: optional "full" or "excluded"

    How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

    • "full"

    • "excluded"

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

  • use_cache: optional boolean

    Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

Beta Web Fetch Tool Result Block

• BetaWebFetchToolResultBlock object

  • type: "web_fetch_tool_result"

    default: web_fetch_tool_result

  • content: BetaWebFetchToolResultErrorBlock or BetaWebFetchBlock

    • BetaWebFetchToolResultErrorBlock object

      • type: "web_fetch_tool_result_error"

        default: web_fetch_tool_result_error

      • error_code: BetaWebFetchToolResultErrorCode

        • "invalid_tool_input"

        • "url_too_long"

        • "url_not_allowed"

        • "url_not_in_prior_context"

        • "url_not_accessible"

        • "unsupported_content_type"

        • "too_many_requests"

        • "max_uses_exceeded"

        • "unavailable"

        • "content_too_large"

    • BetaWebFetchBlock object

      • type: "web_fetch_result"

        default: web_fetch_result

      • content: BetaDocumentBlock

        • type: "document"

          default: document

        • citations: BetaCitationConfig or null

          Citation configuration for the document

          • enabled: boolean

            default: false

        • source: BetaBase64PDFSource or BetaPlainTextSource

          • BetaBase64PDFSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "application/pdf"

          • BetaPlainTextSource object

            • type: "text"

            • data: string

            • media_type: "text/plain"

        • title: string or null

          The title of the document

      • retrieved_at: string or null

        ISO 8601 timestamp when the content was retrieved

      • url: string

        Fetched content URL

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

    Tool invocation directly from the model.

    • BetaDirectCaller object

      Tool invocation directly from the model.

      • type: "direct"

    • BetaServerToolCaller object

      Tool invocation generated by a server-side tool.

      • type: "code_execution_20250825"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaServerToolCaller20260120 object

      • type: "code_execution_20260120"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Web Fetch Tool Result Block Param

• BetaWebFetchToolResultBlockParam object

  • type: "web_fetch_tool_result"

  • content: BetaWebFetchToolResultErrorBlockParam or BetaWebFetchBlockParam

    • BetaWebFetchToolResultErrorBlockParam object

      • type: "web_fetch_tool_result_error"

      • error_code: BetaWebFetchToolResultErrorCode

        • "invalid_tool_input"

        • "url_too_long"

        • "url_not_allowed"

        • "url_not_in_prior_context"

        • "url_not_accessible"

        • "unsupported_content_type"

        • "too_many_requests"

        • "max_uses_exceeded"

        • "unavailable"

        • "content_too_large"

    • BetaWebFetchBlockParam object

      • type: "web_fetch_result"

      • content: BetaRequestDocumentBlock

        • type: "document"

        • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

          • BetaBase64PDFSource object

            • type: "base64"

            • data: string

              format: byte

            • media_type: "application/pdf"

          • BetaPlainTextSource object

            • type: "text"

            • data: string

            • media_type: "text/plain"

          • BetaContentBlockSource object

            • type: "content"

            • content: string or array of BetaContentBlockSourceContent

              • string

              • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

                • BetaTextBlockParam object

                  • type: "text"

                  • text: string

                    minLength: 1

                  • cache_control: optional BetaCacheControlEphemeral or null

                    Create a cache control breakpoint at this content block.

                    • type: "ephemeral"

                    • ttl: optional "5m" or "1h"

                      The time-to-live for the cache control breakpoint.

                      This may be one the following values:

                      • 5m: 5 minutes
                      • 1h: 1 hour

                      Defaults to 5m. See prompt caching pricing for details.

                      • "5m"

                      • "1h"

                  • citations: optional array of BetaTextCitationParam or null

                    • BetaCitationCharLocationParam object

                      • type: "char_location"

                      • cited_text: string

                      • document_index: number

                        minimum: 0

                      • document_title: string or null

                        maxLength: 500, minLength: 1

                      • end_char_index: number

                      • start_char_index: number

                        minimum: 0

                    • BetaCitationPageLocationParam object

                      • type: "page_location"

                      • cited_text: string

                      • document_index: number

                        minimum: 0

                      • document_title: string or null

                        maxLength: 500, minLength: 1

                      • end_page_number: number

                      • start_page_number: number

                        minimum: 1

                    • BetaCitationContentBlockLocationParam object

                      • type: "content_block_location"

                      • cited_text: string

                        The full text of the cited block range, concatenated.

                        Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                      • document_index: number

                        minimum: 0

                      • document_title: string or null

                        maxLength: 500, minLength: 1

                      • end_block_index: number

                        Exclusive 0-based end index of the cited block range in the source's content array.

                        Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

                      • start_block_index: number

                        0-based index of the first cited block in the source's content array.

                        minimum: 0

                    • BetaCitationWebSearchResultLocationParam object

                      • type: "web_search_result_location"

                      • cited_text: string

                      • encrypted_index: string

                      • title: string or null

                        maxLength: 512, minLength: 1

                      • url: string

                        minLength: 1

                    • BetaCitationSearchResultLocationParam object

                      • type: "search_result_location"

                      • cited_text: string

                        The full text of the cited block range, concatenated.

                        Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                      • end_block_index: number

                        Exclusive 0-based end index of the cited block range in the source's content array.

                        Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

                      • search_result_index: number

                        0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

                        Counted separately from document_index; server-side web search results are not included in this count.

                        minimum: 0

                      • source: string

                      • start_block_index: number

                        0-based index of the first cited block in the source's content array.

                        minimum: 0

                      • title: string or null

                • BetaImageBlockParam object

                  • type: "image"

                  • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

                    • BetaBase64ImageSource object

                      • type: "base64"

                      • data: string

                        format: byte

                      • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

                        • "image/jpeg"

                        • "image/png"

                        • "image/gif"

                        • "image/webp"

                    • BetaURLImageSource object

                      • type: "url"

                      • url: string

                    • BetaFileImageSource object

                      • type: "file"

                      • file_id: string

                  • cache_control: optional BetaCacheControlEphemeral or null

                    Create a cache control breakpoint at this content block.

                  • transformations: optional BetaImageTransformationsParam or null

                    Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

                    • oversized_image: optional "downsize" or "error"

                      What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

                      • "downsize"

                      • "error"

          • BetaURLPDFSource object

            • type: "url"

            • url: string

          • BetaFileDocumentSource object

            • type: "file"

            • file_id: string

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

          • enabled: optional boolean

        • context: optional string or null

          minLength: 1

        • title: optional string or null

          maxLength: 500, minLength: 1

      • url: string

        Fetched content URL

      • retrieved_at: optional string or null

        ISO 8601 timestamp when the content was retrieved

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

  • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

    Tool invocation directly from the model.

    • BetaDirectCaller object

      Tool invocation directly from the model.

      • type: "direct"

    • BetaServerToolCaller object

      Tool invocation generated by a server-side tool.

      • type: "code_execution_20250825"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaServerToolCaller20260120 object

      • type: "code_execution_20260120"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Web Fetch Tool Result Error Block

• BetaWebFetchToolResultErrorBlock object

  • type: "web_fetch_tool_result_error"

    default: web_fetch_tool_result_error

  • error_code: BetaWebFetchToolResultErrorCode

    • "invalid_tool_input"

    • "url_too_long"

    • "url_not_allowed"

    • "url_not_in_prior_context"

    • "url_not_accessible"

    • "unsupported_content_type"

    • "too_many_requests"

    • "max_uses_exceeded"

    • "unavailable"

    • "content_too_large"

Beta Web Fetch Tool Result Error Block Param

• BetaWebFetchToolResultErrorBlockParam object

  • type: "web_fetch_tool_result_error"

  • error_code: BetaWebFetchToolResultErrorCode

    • "invalid_tool_input"

    • "url_too_long"

    • "url_not_allowed"

    • "url_not_in_prior_context"

    • "url_not_accessible"

    • "unsupported_content_type"

    • "too_many_requests"

    • "max_uses_exceeded"

    • "unavailable"

    • "content_too_large"

Beta Web Fetch Tool Result Error Code

• BetaWebFetchToolResultErrorCode = "invalid_tool_input" or "url_too_long" or "url_not_allowed" or 7 more

  • "invalid_tool_input"

  • "url_too_long"

  • "url_not_allowed"

  • "url_not_in_prior_context"

  • "url_not_accessible"

  • "unsupported_content_type"

  • "too_many_requests"

  • "max_uses_exceeded"

  • "unavailable"

  • "content_too_large"

Beta Web Search Result Block

• BetaWebSearchResultBlock object

  • type: "web_search_result"

    default: web_search_result

  • encrypted_content: string

  • page_age: string or null

  • title: string

  • url: string

Beta Web Search Result Block Param

• BetaWebSearchResultBlockParam object

  • type: "web_search_result"

  • encrypted_content: string

  • title: string

  • url: string

  • page_age: optional string or null

Beta Web Search Tool 20250305

• BetaWebSearchTool20250305 object

  • type: "web_search_20250305"

  • name: "web_search"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • allowed_domains: optional array of string or null

    If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

  • blocked_domains: optional array of string or null

    If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • max_uses: optional number or null

    Maximum number of times the tool can be used in the API request.

    exclusiveMinimum: 0

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

  • user_location: optional BetaUserLocation or null

    Parameters for the user's location. Used to provide more relevant search results.

    • type: "approximate"

    • city: optional string or null

      The city of the user.

      maxLength: 255, minLength: 1

    • country: optional string or null

      The two letter ISO country code of the user.

      maxLength: 2, minLength: 2

    • region: optional string or null

      The region of the user.

      maxLength: 255, minLength: 1

    • timezone: optional string or null

      The IANA timezone of the user.

      maxLength: 255, minLength: 1

Beta Web Search Tool 20260209

• BetaWebSearchTool20260209 object

  • type: "web_search_20260209"

  • name: "web_search"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • allowed_domains: optional array of string or null

    If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

  • blocked_domains: optional array of string or null

    If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • max_uses: optional number or null

    Maximum number of times the tool can be used in the API request.

    exclusiveMinimum: 0

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

  • user_location: optional BetaUserLocation or null

    Parameters for the user's location. Used to provide more relevant search results.

    • type: "approximate"

    • city: optional string or null

      The city of the user.

      maxLength: 255, minLength: 1

    • country: optional string or null

      The two letter ISO country code of the user.

      maxLength: 2, minLength: 2

    • region: optional string or null

      The region of the user.

      maxLength: 255, minLength: 1

    • timezone: optional string or null

      The IANA timezone of the user.

      maxLength: 255, minLength: 1

Beta Web Search Tool 20260318

• BetaWebSearchTool20260318 object

  • type: "web_search_20260318"

  • name: "web_search"

    Name of the tool.

    This is how the tool will be called by the model and in tool_use blocks.

  • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

    • "direct"

    • "code_execution_20250825"

    • "code_execution_20260120"

    • "code_execution_20260521"

  • allowed_domains: optional array of string or null

    If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

  • blocked_domains: optional array of string or null

    If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • defer_loading: optional boolean

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  • max_uses: optional number or null

    Maximum number of times the tool can be used in the API request.

    exclusiveMinimum: 0

  • response_inclusion: optional "full" or "excluded"

    How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

    • "full"

    • "excluded"

  • strict: optional boolean

    When true, guarantees schema validation on tool names and inputs

  • user_location: optional BetaUserLocation or null

    Parameters for the user's location. Used to provide more relevant search results.

    • type: "approximate"

    • city: optional string or null

      The city of the user.

      maxLength: 255, minLength: 1

    • country: optional string or null

      The two letter ISO country code of the user.

      maxLength: 2, minLength: 2

    • region: optional string or null

      The region of the user.

      maxLength: 255, minLength: 1

    • timezone: optional string or null

      The IANA timezone of the user.

      maxLength: 255, minLength: 1

Beta Web Search Tool Request Error

• BetaWebSearchToolRequestError object

  • type: "web_search_tool_result_error"

  • error_code: BetaWebSearchToolResultErrorCode

    • "invalid_tool_input"

    • "unavailable"

    • "max_uses_exceeded"

    • "too_many_requests"

    • "query_too_long"

    • "request_too_large"

Beta Web Search Tool Result Block

• BetaWebSearchToolResultBlock object

  • type: "web_search_tool_result"

    default: web_search_tool_result

  • content: BetaWebSearchToolResultBlockContent

    • BetaWebSearchToolResultError object

      • type: "web_search_tool_result_error"

        default: web_search_tool_result_error

      • error_code: BetaWebSearchToolResultErrorCode

        • "invalid_tool_input"

        • "unavailable"

        • "max_uses_exceeded"

        • "too_many_requests"

        • "query_too_long"

        • "request_too_large"

    • array of BetaWebSearchResultBlock

      • type: "web_search_result"

        default: web_search_result

      • encrypted_content: string

      • page_age: string or null

      • title: string

      • url: string

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

    Tool invocation directly from the model.

    • BetaDirectCaller object

      Tool invocation directly from the model.

      • type: "direct"

    • BetaServerToolCaller object

      Tool invocation generated by a server-side tool.

      • type: "code_execution_20250825"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaServerToolCaller20260120 object

      • type: "code_execution_20260120"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Web Search Tool Result Block Content

• BetaWebSearchToolResultBlockContent = BetaWebSearchToolResultError or array of BetaWebSearchResultBlock

  • BetaWebSearchToolResultError object

    • type: "web_search_tool_result_error"

      default: web_search_tool_result_error

    • error_code: BetaWebSearchToolResultErrorCode

      • "invalid_tool_input"

      • "unavailable"

      • "max_uses_exceeded"

      • "too_many_requests"

      • "query_too_long"

      • "request_too_large"

  • array of BetaWebSearchResultBlock

    • type: "web_search_result"

      default: web_search_result

    • encrypted_content: string

    • page_age: string or null

    • title: string

    • url: string

Beta Web Search Tool Result Block Param

• BetaWebSearchToolResultBlockParam object

  • type: "web_search_tool_result"

  • content: BetaWebSearchToolResultBlockParamContent

    • ResultBlock = array of BetaWebSearchResultBlockParam

      • type: "web_search_result"

      • encrypted_content: string

      • title: string

      • url: string

      • page_age: optional string or null

    • BetaWebSearchToolRequestError object

      • type: "web_search_tool_result_error"

      • error_code: BetaWebSearchToolResultErrorCode

        • "invalid_tool_input"

        • "unavailable"

        • "max_uses_exceeded"

        • "too_many_requests"

        • "query_too_long"

        • "request_too_large"

  • tool_use_id: string

    pattern: ^srvtoolu_[a-zA-Z0-9_]+$

  • cache_control: optional BetaCacheControlEphemeral or null

    Create a cache control breakpoint at this content block.

    • type: "ephemeral"

    • ttl: optional "5m" or "1h"

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      • 5m: 5 minutes
      • 1h: 1 hour

      Defaults to 5m. See prompt caching pricing for details.

      • "5m"

      • "1h"

  • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

    Tool invocation directly from the model.

    • BetaDirectCaller object

      Tool invocation directly from the model.

      • type: "direct"

    • BetaServerToolCaller object

      Tool invocation generated by a server-side tool.

      • type: "code_execution_20250825"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

    • BetaServerToolCaller20260120 object

      • type: "code_execution_20260120"

      • tool_id: string

        pattern: ^srvtoolu_[a-zA-Z0-9_]+$

Beta Web Search Tool Result Block Param Content

• BetaWebSearchToolResultBlockParamContent = array of BetaWebSearchResultBlockParam or BetaWebSearchToolRequestError

  • ResultBlock = array of BetaWebSearchResultBlockParam

    • type: "web_search_result"

    • encrypted_content: string

    • title: string

    • url: string

    • page_age: optional string or null

  • BetaWebSearchToolRequestError object

    • type: "web_search_tool_result_error"

    • error_code: BetaWebSearchToolResultErrorCode

      • "invalid_tool_input"

      • "unavailable"

      • "max_uses_exceeded"

      • "too_many_requests"

      • "query_too_long"

      • "request_too_large"

Beta Web Search Tool Result Error

• BetaWebSearchToolResultError object

  • type: "web_search_tool_result_error"

    default: web_search_tool_result_error

  • error_code: BetaWebSearchToolResultErrorCode

    • "invalid_tool_input"

    • "unavailable"

    • "max_uses_exceeded"

    • "too_many_requests"

    • "query_too_long"

    • "request_too_large"

Beta Web Search Tool Result Error Code

• BetaWebSearchToolResultErrorCode = "invalid_tool_input" or "unavailable" or "max_uses_exceeded" or 3 more

  • "invalid_tool_input"

  • "unavailable"

  • "max_uses_exceeded"

  • "too_many_requests"

  • "query_too_long"

  • "request_too_large"

Messages › Batches

Create a Message Batch

POST /v1/messages/batches

Send a batch of Message creation requests.

The Message Batches API can be used to process multiple Messages API requests at once. Once a Message Batch is created, it begins processing immediately. Batches can take up to 24 hours to complete.

Learn more about the Message Batches API in our user guide

Headers

• "anthropic-beta": optional array of AnthropicBeta

  Optional header to specify the beta version(s) you want to use.

  • string

  • "message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 42 more

    • "message-batches-2024-09-24"

    • "prompt-caching-2024-07-31"

    • "computer-use-2024-10-22"

    • "computer-use-2025-01-24"

    • "pdfs-2024-09-25"

    • "token-counting-2024-11-01"

    • "token-efficient-tools-2025-02-19"

    • "output-128k-2025-02-19"

    • "files-api-2025-04-14"

    • "mcp-client-2025-04-04"

    • "mcp-client-2025-11-20"

    • "dev-full-thinking-2025-05-14"

    • "interleaved-thinking-2025-05-14"

    • "code-execution-2025-05-22"

    • "extended-cache-ttl-2025-04-11"

    • "context-1m-2025-08-07"

    • "context-management-2025-06-27"

    • "model-context-window-exceeded-2025-08-26"

    • "skills-2025-10-02"

    • "fast-mode-2026-02-01"

    • "output-300k-2026-03-24"

    • "user-profiles-2026-03-24"

    • "user-profiles-2026-08-18"

    • "user-profiles-2026-09-04"

    • "advisor-tool-2026-03-01"

    • "managed-agents-2026-04-01"

    • "cache-diagnosis-2026-04-07"

    • "dreaming-2026-04-21"

    • "thinking-token-count-2026-05-13"

    • "server-side-fallback-2026-06-01"

    • "server-side-fallback-2026-07-01"

    • "fallback-credit-2026-06-01"

    • "fallback-credit-2026-07-01"

    • "agent-memory-2026-07-22"

    • "mid-conversation-tool-changes-2026-07-01"

    • "compact-2026-01-12"

    • "computer-use-2025-11-24"

    • "mcp-tunnels-2026-06-22"

    • "structured-outputs-2025-11-13"

    • "task-budgets-2026-03-13"

    • "thinking-display-updates-2026-08-18"

    • "ce-user-management-2026-07-13"

    • "mid-conversation-output-config-2026-07-01"

    • "thinking-binding-controls-2026-08-01"

    • "mid-conversation-system-clear-at-2026-08-21"

• "anthropic-user-profile-id": optional string

  The user profile ID to attribute the requests in this batch to. Use when acting on behalf of a party other than your organization. Requires the user-profiles beta header. Applies to every request in the batch; an individual request whose user_profile_id body field conflicts with this header is errored.

• "anthropic-workspace-id": optional string

Body parameters

• requests: array of object

  List of requests for prompt completion. Each is an individual request to create a Message.

  maxItems: 100000, minItems: 1

  • custom_id: string

    Developer-provided ID created for each request in a Message Batch. Useful for matching results to requests, as results may be given out of request order.

    Must be unique for each request within the Message Batch.

    maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,64}$

  • params: object

    Messages API creation parameters for the individual request.

    See the Messages API reference for full documentation on available parameters.

    • max_tokens: number

      The maximum number of tokens to generate before stopping.

      Note that our models may stop before reaching this maximum. This parameter only specifies the absolute maximum number of tokens to generate.

      Set to 0 to populate the prompt cache without generating a response.

      Different models have different maximum values for this parameter. See models for details.

      minimum: 0

    • messages: array of BetaMessageParam

      Input messages.

      Our models are trained to operate on alternating user and assistant conversational turns. When creating a new Message, you specify the prior conversational turns with the messages parameter, and the model then generates the next Message in the conversation. Consecutive user or assistant turns in your request will be combined into a single turn.

      Each input message must be an object with a role and content. You can specify a single user-role message, or you can include multiple user and assistant messages.

      If the final message uses the assistant role, the response content will continue immediately from the content in that message. This can be used to constrain part of the model's response.

      Example with a single user message:

      [{"role": "user", "content": "Hello, Claude"}]

      Example with multiple conversational turns:

      [
        {"role": "user", "content": "Hello there."},
        {"role": "assistant", "content": "Hi, I'm Claude. How can I help you?"},
        {"role": "user", "content": "Can you explain LLMs in plain English?"},
      ]

      Example with a partially-filled response from Claude:

      [
        {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
        {"role": "assistant", "content": "The best answer is ("},
      ]

      Each input message content may be either a single string or an array of content blocks, where each block has a specific type. Using a string for content is shorthand for an array of one content block of type "text". The following input messages are equivalent:

      {"role": "user", "content": "Hello, Claude"}

      {"role": "user", "content": [{"type": "text", "text": "Hello, Claude"}]}

      See input examples.

      Note that if you want to include a system prompt, you can use the top-level system parameter — there is no "system" role for input messages in the Messages API.

      There is a limit of 100,000 messages in a single request.

      • content: string or array of BetaContentBlockParam

        • string

        • array of BetaContentBlockParam

          • BetaTextBlockParam object

            • type: "text"

            • text: string

              minLength: 1

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

              • type: "ephemeral"

              • ttl: optional "5m" or "1h"

                The time-to-live for the cache control breakpoint.

                This may be one the following values:

                • 5m: 5 minutes
                • 1h: 1 hour

                Defaults to 5m. See prompt caching pricing for details.

                • "5m"

                • "1h"

            • citations: optional array of BetaTextCitationParam or null

              • BetaCitationCharLocationParam object

                • type: "char_location"

                • cited_text: string

                • document_index: number

                  minimum: 0

                • document_title: string or null

                  maxLength: 500, minLength: 1

                • end_char_index: number

                • start_char_index: number

                  minimum: 0

              • BetaCitationPageLocationParam object

                • type: "page_location"

                • cited_text: string

                • document_index: number

                  minimum: 0

                • document_title: string or null

                  maxLength: 500, minLength: 1

                • end_page_number: number

                • start_page_number: number

                  minimum: 1

              • BetaCitationContentBlockLocationParam object

                • type: "content_block_location"

                • cited_text: string

                  The full text of the cited block range, concatenated.

                  Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                • document_index: number

                  minimum: 0

                • document_title: string or null

                  maxLength: 500, minLength: 1

                • end_block_index: number

                  Exclusive 0-based end index of the cited block range in the source's content array.

                  Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

                • start_block_index: number

                  0-based index of the first cited block in the source's content array.

                  minimum: 0

              • BetaCitationWebSearchResultLocationParam object

                • type: "web_search_result_location"

                • cited_text: string

                • encrypted_index: string

                • title: string or null

                  maxLength: 512, minLength: 1

                • url: string

                  minLength: 1

              • BetaCitationSearchResultLocationParam object

                • type: "search_result_location"

                • cited_text: string

                  The full text of the cited block range, concatenated.

                  Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                • end_block_index: number

                  Exclusive 0-based end index of the cited block range in the source's content array.

                  Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

                • search_result_index: number

                  0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

                  Counted separately from document_index; server-side web search results are not included in this count.

                  minimum: 0

                • source: string

                • start_block_index: number

                  0-based index of the first cited block in the source's content array.

                  minimum: 0

                • title: string or null

          • BetaImageBlockParam object

            • type: "image"

            • source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

              • BetaBase64ImageSource object

                • type: "base64"

                • data: string

                  format: byte

                • media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

                  • "image/jpeg"

                  • "image/png"

                  • "image/gif"

                  • "image/webp"

              • BetaURLImageSource object

                • type: "url"

                • url: string

              • BetaFileImageSource object

                • type: "file"

                • file_id: string

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • transformations: optional BetaImageTransformationsParam or null

              Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

              • oversized_image: optional "downsize" or "error"

                What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

                • "downsize"

                • "error"

          • BetaRequestDocumentBlock object

            • type: "document"

            • source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

              • BetaBase64PDFSource object

                • type: "base64"

                • data: string

                  format: byte

                • media_type: "application/pdf"

              • BetaPlainTextSource object

                • type: "text"

                • data: string

                • media_type: "text/plain"

              • BetaContentBlockSource object

                • type: "content"

                • content: string or array of BetaContentBlockSourceContent

                  • string

                  • BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

                    • BetaTextBlockParam object

                    • BetaImageBlockParam object

              • BetaURLPDFSource object

                • type: "url"

                • url: string

              • BetaFileDocumentSource object

                • type: "file"

                • file_id: string

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • citations: optional BetaCitationsConfigParam or null

              • enabled: optional boolean

            • context: optional string or null

              minLength: 1

            • title: optional string or null

              maxLength: 500, minLength: 1

          • BetaSearchResultBlockParam object

            • type: "search_result"

            • content: array of BetaTextBlockParam

              • type: "text"

              • text: string

                minLength: 1

              • cache_control: optional BetaCacheControlEphemeral or null

                Create a cache control breakpoint at this content block.

              • citations: optional array of BetaTextCitationParam or null

            • source: string

            • title: string

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • citations: optional BetaCitationsConfigParam

          • BetaThinkingBlockParam object

            • type: "thinking"

            • signature: string

              The signature value of this thinking block, exactly as returned by the API in a previous response. Used to verify that the block was generated by Claude.

              Thinking blocks must be passed back unmodified and in their original order; a modified block results in a 400 invalid_request_error.

            • thinking: string

              The thinking text of this block as returned by the API.

          • BetaRedactedThinkingBlockParam object

            • type: "redacted_thinking"

            • data: string

              The data value of this redacted thinking block, exactly as returned by the API in a previous response. Opaque and encrypted; pass it back unchanged.

          • BetaToolUseBlockParam object

            • type: "tool_use"

            • id: string

              pattern: ^[a-zA-Z0-9_-]+$

            • input: map[unknown]

            • name: string

              maxLength: 200, minLength: 1

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

              Tool invocation directly from the model.

              • BetaDirectCaller object

                Tool invocation directly from the model.

                • type: "direct"

              • BetaServerToolCaller object

                Tool invocation generated by a server-side tool.

                • type: "code_execution_20250825"

                • tool_id: string

                  pattern: ^srvtoolu_[a-zA-Z0-9_]+$

              • BetaServerToolCaller20260120 object

                • type: "code_execution_20260120"

                • tool_id: string

                  pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • toolset_name: optional string or null

              For a toolset member tool_use, the toolset family this member belongs to.

              maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

          • BetaToolResultBlockParam object

            • type: "tool_result"

            • tool_use_id: string

              pattern: ^[a-zA-Z0-9_-]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • content: optional string or array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

              • string

              • array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

                • BetaTextBlockParam object

                • BetaImageBlockParam object

                • BetaSearchResultBlockParam object

                • BetaRequestDocumentBlock object

                • BetaToolReferenceBlockParam object

                  Tool reference block that can be included in tool_result content.

                  • type: "tool_reference"

                  • tool_name: string

                    maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

                  • cache_control: optional BetaCacheControlEphemeral or null

                    Create a cache control breakpoint at this content block.

                • BetaBrowserStateBlockParam object

                  The caller's browser state after a browser toolset member call — the full inventory of open tabs, which tab is active, and any side effects (tabs opened, download state changes) the call produced.

                  At most one per tool_result, only on a non-error result answering a browser toolset member tool_use. The server renders the model-visible text from it; the model never sees the raw fields.

                  • type: "browser_state"

                  • tabs: array of BetaBrowserStateTabEntry

                    All tabs open in the browser after this call — the full inventory, not a delta. May be empty. Whenever non-empty, exactly one entry carries active: true.

                    maxItems: 100

                    • tab_id: string

                      The caller-assigned identifier for this tab, unique within the inventory.

                      maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                    • title: string

                      The title of the page the tab is showing. May be empty.

                      maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                    • url: string

                      The URL of the page the tab is showing. May be empty.

                      maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                    • active: optional boolean

                      Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

                  • cache_control: optional BetaCacheControlEphemeral or null

                    Create a cache control breakpoint at this content block.

                  • state_changes: optional array of BetaBrowserStateChange or null

                    Tabs opened and download state changes during this call. "Nothing to report" is expressed by omitting the field, never by an empty list.

                    maxItems: 200, minItems: 1

                    • BetaBrowserStateChangeTabOpened object

                      A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

                      Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

                      • type: "tab_opened"

                      • tab_id: string

                        The tab_id of the opened tab, present in tabs.

                        maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                    • BetaBrowserStateChangeDownloadStarted object

                      A file download that started during this call.

                      • type: "download_started"

                      • download_id: string

                        The caller-assigned identifier for this download, stable across the state changes reporting it.

                        maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                      • url: string

                        The final post-redirect URL the download was served from.

                        maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                    • BetaBrowserStateChangeDownloadCompleted object

                      A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

                      • type: "download_completed"

                      • download_id: string

                        The caller-assigned identifier for this download, stable across the state changes reporting it.

                        maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                      • url: string

                        The final post-redirect URL the download was served from.

                        maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                      • path: optional string or null

                        Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

                        pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

                      • size_bytes: optional number or null

                        The completed download's size.

                        minimum: 0

                    • BetaBrowserStateChangeDownloadFailed object

                      A file download that failed — or was cancelled — during this call.

                      • type: "download_failed"

                      • download_id: string

                        The caller-assigned identifier for this download, stable across the state changes reporting it.

                        maxLength: 4096, minLength: 1, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                      • url: string

                        The final post-redirect URL the download was served from.

                        maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

                      • error: optional string or null

                        The failure or cancellation detail, when known.

                        pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$, maxLength: 4096

            • is_error: optional boolean

            • toolset_name: optional string or null

              For a toolset member tool_result, the toolset family of the paired tool_use.

              maxLength: 64, minLength: 1, pattern: ^[a-zA-Z0-9_-]+$

          • BetaServerToolUseBlockParam object

            • type: "server_tool_use"

            • id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • input: map[unknown]

            • name: "advisor" or "web_search" or "web_fetch" or 5 more

              • "advisor"

              • "web_search"

              • "web_fetch"

              • "code_execution"

              • "bash_code_execution"

              • "text_editor_code_execution"

              • "tool_search_tool_regex"

              • "tool_search_tool_bm25"

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

              Tool invocation directly from the model.

              • BetaDirectCaller object

                Tool invocation directly from the model.

              • BetaServerToolCaller object

                Tool invocation generated by a server-side tool.

              • BetaServerToolCaller20260120 object

          • BetaWebSearchToolResultBlockParam object

            • type: "web_search_tool_result"

            • content: BetaWebSearchToolResultBlockParamContent

              • ResultBlock = array of BetaWebSearchResultBlockParam

                • type: "web_search_result"

                • encrypted_content: string

                • title: string

                • url: string

                • page_age: optional string or null

              • BetaWebSearchToolRequestError object

                • type: "web_search_tool_result_error"

                • error_code: BetaWebSearchToolResultErrorCode

                  • "invalid_tool_input"

                  • "unavailable"

                  • "max_uses_exceeded"

                  • "too_many_requests"

                  • "query_too_long"

                  • "request_too_large"

            • tool_use_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

              Tool invocation directly from the model.

              • BetaDirectCaller object

                Tool invocation directly from the model.

              • BetaServerToolCaller object

                Tool invocation generated by a server-side tool.

              • BetaServerToolCaller20260120 object

          • BetaWebFetchToolResultBlockParam object

            • type: "web_fetch_tool_result"

            • content: BetaWebFetchToolResultErrorBlockParam or BetaWebFetchBlockParam

              • BetaWebFetchToolResultErrorBlockParam object

                • type: "web_fetch_tool_result_error"

                • error_code: BetaWebFetchToolResultErrorCode

                  • "invalid_tool_input"

                  • "url_too_long"

                  • "url_not_allowed"

                  • "url_not_in_prior_context"

                  • "url_not_accessible"

                  • "unsupported_content_type"

                  • "too_many_requests"

                  • "max_uses_exceeded"

                  • "unavailable"

                  • "content_too_large"

              • BetaWebFetchBlockParam object

                • type: "web_fetch_result"

                • content: BetaRequestDocumentBlock

                • url: string

                  Fetched content URL

                • retrieved_at: optional string or null

                  ISO 8601 timestamp when the content was retrieved

            • tool_use_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

              Tool invocation directly from the model.

              • BetaDirectCaller object

                Tool invocation directly from the model.

              • BetaServerToolCaller object

                Tool invocation generated by a server-side tool.

              • BetaServerToolCaller20260120 object

          • BetaAdvisorToolResultBlockParam object

            • type: "advisor_tool_result"

            • content: BetaAdvisorToolResultErrorParam or BetaAdvisorResultBlockParam or BetaAdvisorRedactedResultBlockParam

              • BetaAdvisorToolResultErrorParam object

                • type: "advisor_tool_result_error"

                • error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

                  • "max_uses_exceeded"

                  • "prompt_too_long"

                  • "too_many_requests"

                  • "overloaded"

                  • "unavailable"

                  • "execution_time_exceeded"

                  • "model_not_found"

              • BetaAdvisorResultBlockParam object

                • type: "advisor_result"

                • text: string

                • stop_reason: optional string or null

              • BetaAdvisorRedactedResultBlockParam object

                • type: "advisor_redacted_result"

                • encrypted_content: string

                  Opaque blob produced by a prior response; must be round-tripped verbatim.

                • stop_reason: optional string or null

            • tool_use_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaCodeExecutionToolResultBlockParam object

            • type: "code_execution_tool_result"

            • content: BetaCodeExecutionToolResultBlockParamContent

              Code execution result with encrypted stdout for PFC + web_search results.

              • BetaCodeExecutionToolResultErrorParam object

                • type: "code_execution_tool_result_error"

                • error_code: BetaCodeExecutionToolResultErrorCode

                  • "invalid_tool_input"

                  • "unavailable"

                  • "too_many_requests"

                  • "execution_time_exceeded"

              • BetaCodeExecutionResultBlockParam object

                • type: "code_execution_result"

                • content: array of BetaCodeExecutionOutputBlockParam

                  • type: "code_execution_output"

                  • file_id: string

                • return_code: number

                • stderr: string

                • stdout: string

              • BetaEncryptedCodeExecutionResultBlockParam object

                Code execution result with encrypted stdout for PFC + web_search results.

                • type: "encrypted_code_execution_result"

                • content: array of BetaCodeExecutionOutputBlockParam

                  • type: "code_execution_output"

                  • file_id: string

                • encrypted_stdout: string

                • return_code: number

                • stderr: string

            • tool_use_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaBashCodeExecutionToolResultBlockParam object

            • type: "bash_code_execution_tool_result"

            • content: BetaBashCodeExecutionToolResultErrorParam or BetaBashCodeExecutionResultBlockParam

              • BetaBashCodeExecutionToolResultErrorParam object

                • type: "bash_code_execution_tool_result_error"

                • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

                  • "invalid_tool_input"

                  • "unavailable"

                  • "too_many_requests"

                  • "execution_time_exceeded"

                  • "output_file_too_large"

              • BetaBashCodeExecutionResultBlockParam object

                • type: "bash_code_execution_result"

                • content: array of BetaBashCodeExecutionOutputBlockParam

                  • type: "bash_code_execution_output"

                  • file_id: string

                • return_code: number

                • stderr: string

                • stdout: string

            • tool_use_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaTextEditorCodeExecutionToolResultBlockParam object

            • type: "text_editor_code_execution_tool_result"

            • content: BetaTextEditorCodeExecutionToolResultErrorParam or BetaTextEditorCodeExecutionViewResultBlockParam or BetaTextEditorCodeExecutionCreateResultBlockParam or BetaTextEditorCodeExecutionStrReplaceResultBlockParam

              • BetaTextEditorCodeExecutionToolResultErrorParam object

                • type: "text_editor_code_execution_tool_result_error"

                • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

                  • "invalid_tool_input"

                  • "unavailable"

                  • "too_many_requests"

                  • "execution_time_exceeded"

                  • "file_not_found"

                • error_message: optional string or null

              • BetaTextEditorCodeExecutionViewResultBlockParam object

                • type: "text_editor_code_execution_view_result"

                • content: string

                • file_type: "text" or "image" or "pdf"

                  • "text"

                  • "image"

                  • "pdf"

                • num_lines: optional number or null

                • start_line: optional number or null

                • total_lines: optional number or null

              • BetaTextEditorCodeExecutionCreateResultBlockParam object

                • type: "text_editor_code_execution_create_result"

                • is_file_update: boolean

              • BetaTextEditorCodeExecutionStrReplaceResultBlockParam object

                • type: "text_editor_code_execution_str_replace_result"

                • lines: optional array of string or null

                • new_lines: optional number or null

                • new_start: optional number or null

                • old_lines: optional number or null

                • old_start: optional number or null

            • tool_use_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaToolSearchToolResultBlockParam object

            • type: "tool_search_tool_result"

            • content: BetaToolSearchToolResultErrorParam or BetaToolSearchToolSearchResultBlockParam

              • BetaToolSearchToolResultErrorParam object

                • type: "tool_search_tool_result_error"

                • error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

                  • "invalid_tool_input"

                  • "unavailable"

                  • "too_many_requests"

                  • "execution_time_exceeded"

                • error_message: optional string or null

              • BetaToolSearchToolSearchResultBlockParam object

                • type: "tool_search_tool_search_result"

                • tool_references: array of BetaToolReferenceBlockParam

                  • type: "tool_reference"

                  • tool_name: string

                    maxLength: 256, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,256}$

                  • cache_control: optional BetaCacheControlEphemeral or null

                    Create a cache control breakpoint at this content block.

            • tool_use_id: string

              pattern: ^srvtoolu_[a-zA-Z0-9_]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaMCPToolUseBlockParam object

            • type: "mcp_tool_use"

            • id: string

              pattern: ^[a-zA-Z0-9_-]+$

            • input: map[unknown]

            • name: string

            • server_name: string

              The name of the MCP server

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaRequestMCPToolResultBlockParam object

            • type: "mcp_tool_result"

            • tool_use_id: string

              pattern: ^[a-zA-Z0-9_-]+$

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • content: optional string or array of BetaTextBlockParam

              • string

              • BetaMCPToolResultBlockParamContent = array of BetaTextBlockParam

                • type: "text"

                • text: string

                  minLength: 1

                • cache_control: optional BetaCacheControlEphemeral or null

                  Create a cache control breakpoint at this content block.

                • citations: optional array of BetaTextCitationParam or null

            • is_error: optional boolean

          • BetaContainerUploadBlockParam object

            A content block that represents a file to be uploaded to the container Files uploaded via this block will be available in the container's input directory.

            • type: "container_upload"

            • file_id: string

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaCompactionBlockParam object

            A compaction block containing summary of previous context.

            Users should round-trip these blocks from responses to subsequent requests to maintain context across compaction boundaries.

            When content is None, the block represents a failed compaction. The server treats these as no-ops. Empty string content is not allowed.

            • type: "compaction"

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

            • content: optional string or null

              Summary of previously compacted content, or null if compaction failed

            • encrypted_content: optional string or null

              Opaque metadata from prior compaction, to be round-tripped verbatim

          • BetaRequestToolAdditionBlock object

            Mid-conversation directive to surface a declared tool.

            tool references a tool (or MCP toolset) by name from the request's tools; it is offered to the model from this point in the conversation onward.

            • type: "tool_addition"

            • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

              Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

              • BetaToolChangeToolReference object

                Reference to a single tool the caller declared directly in tools[]. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

                • type: "tool_reference"

                • name: string

                  pattern: ^[a-zA-Z0-9_-]{1,128}$

              • BetaToolChangeMCPToolReference object

                Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

                • type: "mcp_tool_reference"

                • name: string

                • server_name: string

              • BetaToolChangeMCPToolsetReference object

                Reference to every tool in the named MCP server's toolset.

                • type: "mcp_toolset_reference"

                • server_name: string

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaRequestToolRemovalBlock object

            Mid-conversation directive to withdraw a tool.

            tool references a tool (or MCP toolset) by name from the request's tools; it is no longer offered to the model from this point in the conversation onward.

            • type: "tool_removal"

            • tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

              Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

              • BetaToolChangeToolReference object

                Reference to a single tool the caller declared directly in tools[]. Does not accept the composed \{server\}_\{name\} form the server assigns to MCP-resolved tools — use mcp_tool_reference or mcp_toolset_reference for those.

              • BetaToolChangeMCPToolReference object

                Reference to a single MCP tool by its server and remote name — the same server_name/name pair mcp_tool_use carries.

              • BetaToolChangeMCPToolsetReference object

                Reference to every tool in the named MCP server's toolset.

            • cache_control: optional BetaCacheControlEphemeral or null

              Create a cache control breakpoint at this content block.

          • BetaFallbackBlockParam object

            A fallback block echoed back from a prior response.

            Accepted in messages[].content and not rendered into the prompt; not validated against the request's fallbacks chain or top-level model.

            Echo the assistant turn back verbatim, including this block in its original position. The block marks the boundary between content produced before and after a fallback hop, and the server relies on that boundary to validate the turn: when thinking runs flank the boundary, omitting the block merges them into one span the server cannot validate (the request is rejected), and moving it into the middle of a single run is likewise rejected; between non-thinking blocks the block's placement has no validation effect.

            • type: "fallback"

            • from: BetaFallbackInfoParam

              Identifies one hop of a fallback transition.

              • model: Model

                The model that will complete your prompt.

                See models for additional details and options.

                • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

                  The model that will complete your prompt.

                  See models for additional details and options.

                  • "claude-fable-5-1"

                    Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

                  • "claude-mythos-5-1"

                    Our most capable model for cybersecurity and biology research, available through trusted access programs

                  • "claude-sonnet-5"

                    High-performance model for coding and agents

                  • "claude-fable-5"

                    Next generation of intelligence for the hardest knowledge work and coding problems

                  • "claude-mythos-5"

                    Most capable model for cybersecurity and biology research

                  • "claude-opus-5"

                    Powerful intelligence for long-running agents and coding

                  • "claude-opus-4-8"

                    Powerful intelligence for long-running agents and coding

                  • "claude-opus-4-7"

                    Powerful intelligence for long-running agents and coding

                  • "claude-mythos-preview"

                    New class of intelligence, strongest in coding and cybersecurity

                  • "claude-opus-4-6"

                    Powerful intelligence for long-running agents and coding

                  • "claude-sonnet-4-6"

                    Best combination of speed and intelligence

                  • "claude-haiku-4-5"

                    Fastest model with near-frontier intelligence

                  • "claude-haiku-4-5-20251001"

                    Fastest model with near-frontier intelligence

                  • "claude-opus-4-5"

                    Powerful intelligence for long-running agents and coding

                  • "claude-opus-4-5-20251101"

                    Powerful intelligence for long-running agents and coding

                  • "claude-sonnet-4-5"

                    High-performance model for agents and coding

                  • "claude-sonnet-4-5-20250929"

                    High-performance model for agents and coding

                • string

            • to: BetaFallbackInfoParam

              Identifies one hop of a fallback transition.

            • trigger: optional unknown

              The response block's trigger, echoed verbatim. Accepted and ignored by the server; any object or null is allowed.

      • role: "user" or "assistant" or "system"

        • "user"

        • "assistant"

        • "system"

      • clear_at: optional "next_user_message" or "never" or null

        How long this system message's text stays in front of the model. "never" (the default) renders it on every request that includes it. "next_user_message" renders it only for the user turn it follows: once a later role: "user" message exists in messages the message stays in the array (send it unchanged) but is no longer shown to the model. Only permitted on role: "system" messages.

        • "next_user_message"

        • "never"

      • output_config: optional BetaSystemMessageOutputConfig or null

        Per-message output configuration on a role:"system" input message.

        Fields here apply per-turn; format remains top-level only. An empty \{\} is accepted on a message that carries content; a message with neither content nor output_config fields is rejected.

        • effort: optional "low" or "medium" or "high" or 2 more or null

          All possible effort levels.

          • "low"

          • "medium"

          • "high"

          • "xhigh"

          • "max"

    • model: Model

      The model that will complete your prompt.

      See models for additional details and options.

    • cache_control: optional BetaCacheControlEphemeral or null

      Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.

    • container: optional BetaContainerParams or string or null

      Container identifier for reuse across requests.

      • BetaContainerParams object

        Container parameters with skills to be loaded.

        • id: optional string or null

          Container id

        • skills: optional array of BetaSkillParams or null

          List of skills to load in the container

          maxItems: 20

          • type: "anthropic" or "custom"

            Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

            • "anthropic"

            • "custom"

          • skill_id: string

            Skill ID

            maxLength: 64, minLength: 1

          • version: optional string

            Skill version or 'latest' for most recent version

            maxLength: 64, minLength: 1

      • string

    • context_management: optional BetaContextManagementConfig or null

      Context management configuration.

      This allows you to control how Claude manages context across multiple requests, such as whether to clear function results or not.

      • edits: optional array of BetaClearToolUses20250919Edit or BetaClearThinking20251015Edit or BetaCompact20260112Edit

        List of context management edits to apply

        minItems: 0

        • BetaClearToolUses20250919Edit object

          • type: "clear_tool_uses_20250919"

          • clear_at_least: optional BetaInputTokensClearAtLeast or null

            Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

            • type: "input_tokens"

            • value: number

              minimum: 0

          • clear_tool_inputs: optional boolean or array of string or null

            Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

            • boolean

            • array of string

          • exclude_tools: optional array of string or null

            Tool names whose uses are preserved from clearing

          • keep: optional BetaToolUsesKeep

            Number of tool uses to retain in the conversation

            • type: "tool_uses"

            • value: number

              minimum: 0

          • trigger: optional BetaInputTokensTrigger or BetaToolUsesTrigger

            Condition that triggers the context management strategy

            • BetaInputTokensTrigger object

              • type: "input_tokens"

              • value: number

                minimum: 1

            • BetaToolUsesTrigger object

              • type: "tool_uses"

              • value: number

                minimum: 1

        • BetaClearThinking20251015Edit object

          • type: "clear_thinking_20251015"

          • keep: optional BetaThinkingTurns or BetaAllThinkingTurns or "all"

            Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

            • BetaThinkingTurns object

              • type: "thinking_turns"

              • value: number

                minimum: 1

            • BetaAllThinkingTurns object

              • type: "all"

            • "all"

        • BetaCompact20260112Edit object

          Automatically compact older context when reaching the configured trigger threshold.

          • type: "compact_20260112"

          • instructions: optional string or null

            Additional instructions for summarization.

          • pause_after_compaction: optional boolean

            Whether to pause after compaction and return the compaction block to the user.

          • trigger: optional BetaInputTokensTrigger or null

            When to trigger compaction. Defaults to 150000 input tokens.

    • diagnostics: optional BetaDiagnosticsParam or null

      Request-level diagnostics. Currently carries the previous response id for prompt-cache divergence reporting.

      • previous_message_id: optional string or null

        The id (msg_...) from this client's previous /v1/messages response. The server compares that request's prompt fingerprint against this one and returns diagnostics.cache_miss_reason when the prompt-cache prefix could not be reused. Pass null on the first turn to opt in without a prior message to compare.

        maxLength: 256

    • fallback_credit_token: optional string or BetaFallbackCreditTokenParam or null

      The fallback_credit_token from a prior refusal's stop_details.

      When a preceding request was refused and returned a fallback_credit_token, pass that code here on the retry to have the retry's cache-creation tokens for the prefix that was warm on the refused model billed at the cache-read rate. Must be redeemed by the same organization and workspace, with the same request body (optionally extended by one appended assistant message whose content is the partial text — with any trailing whitespace stripped from the final text block — and paired server-tool blocks streamed before the refusal; the appended-assistant form is not available for requests with output_format set or forced tool_choice), on an eligible fallback model, on the same platform, and within 5 minutes of the refusal; a mismatch is a 400. A token minted mid-server-tool-loop whose partial content was continuable may only be redeemed with the appended-assistant form — if an exact-body retry is rejected with a 400 saying the token must be redeemed by continuing the partial response, retry with the appended-assistant form instead.

      When the appended-assistant form is used on a model that otherwise disallows assistant-turn prefill, this token also authorizes that one prefill.

      • string

      • BetaFallbackCreditTokenParam object

        Object form of fallback_credit_token: the token plus a redemption mode.

        Requires anthropic-beta: fallback-credit-2026-07-01; without that header the field accepts the bare string only. The bare string and the mode-less object are equivalent (both select strict), so wrapping an existing token changes nothing by itself.

        • token: string

          The opaque fallback_credit_token from a prior refusal's stop_details — the same string the bare-string form carries.

          maxLength: 2048, minLength: 1

        • mode: optional "strict" or "best_effort"

          How a failing token affects the retry. strict (the default, and the bare-string behavior): a failing redemption is a 400 and the retry is not served. best_effort: the retry is served either way — a token-layer failure no longer rejects the request; the retry proceeds at normal price and the outcome is reported on the response's usage.fallback_credit. Two failures stay hard in both modes: a malformed token, and combining fallback_credit_token with fallbacks.

          • "strict"

          • "best_effort"

    • fallbacks: optional BetaFallbacksParam or null

      Opt-in server-side retry on one or more substitute models when the requested model declines for policy reasons. Tried in order: if the first entry also declines, the second is tried, and so on. The string "default" requests the requested model's server-defined default fallback configuration.

      • array of BetaFallbackParam

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • max_tokens: optional number or null

        • output_config: optional BetaOutputConfig or null

          • effort: optional "low" or "medium" or "high" or 2 more or null

            All possible effort levels.

            • "low"

            • "medium"

            • "high"

            • "xhigh"

            • "max"

          • format: optional BetaJSONOutputFormat or null

            A schema to specify Claude's output format in responses. See structured outputs

            • type: "json_schema"

            • schema: map[unknown]

              The JSON schema of the format

          • task_budget: optional BetaTokenTaskBudget or null

            User-configurable total token budget across contexts.

            • type: "tokens"

              The budget type. Currently only 'tokens' is supported.

            • total: number

              Total token budget across all contexts in the session.

              minimum: 1024

            • remaining: optional number or null

              Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

              minimum: 0

        • speed: optional "standard" or "fast" or null

          Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

          • "standard"

          • "fast"

        • thinking: optional BetaThinkingConfigEnabled or BetaThinkingConfigDisabled or BetaThinkingConfigAdaptive or null

          • BetaThinkingConfigEnabled object

            • type: "enabled"

            • budget_tokens: number

              Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

              Must be ≥1024 and less than max_tokens.

              See extended thinking for details.

              minimum: 1024

            • block_binding: optional BetaThinkingBlockBinding or null

              Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

              • prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

                What happens when a thinking block in messages fails the conversation check: it was created in a different conversation, or the messages before it have changed since. "error" (the default) fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; the model no longer sees the dropped reasoning.

                • "error"

                • "drop_block"

            • display: optional "summarized" or "omitted" or "updates" or null

              Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

              • "summarized"

              • "omitted"

              • "updates"

          • BetaThinkingConfigDisabled object

            • type: "disabled"

          • BetaThinkingConfigAdaptive object

            • type: "adaptive"

            • block_binding: optional BetaThinkingBlockBinding or null

              Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. Every field is optional; an empty object means every default.

            • display: optional "summarized" or "omitted" or "updates" or null

              Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

              • "summarized"

              • "omitted"

              • "updates"

      • Default = "default"

    • inference_geo: optional string or null

      Specifies the geographic region for inference processing. If not specified, the workspace's default_inference_geo is used.

    • mcp_servers: optional array of BetaRequestMCPServerURLDefinition

      MCP servers to be utilized in this request

      maxItems: 20

      • type: "url"

      • name: string

      • url: string

      • authorization_token: optional string or null

      • tool_configuration: optional BetaRequestMCPServerToolConfiguration or null

        • allowed_tools: optional array of string or null

        • enabled: optional boolean or null

    • metadata: optional BetaMetadata

      An object describing metadata about the request.

      • user_id: optional string or null

        An external identifier for the user who is associated with the request.

        This should be a uuid, hash value, or other opaque identifier. Anthropic may use this id to help detect abuse. Do not include any identifying information such as name, email address, or phone number.

        maxLength: 512

    • output_config: optional BetaOutputConfig

      Configuration options for the model's output, such as the output format.

    • service_tier: optional "auto" or "standard_only"

      Determines whether to use priority capacity (if available) or standard capacity for this request.

      Anthropic offers different levels of service for your API requests. See service-tiers for details.

      • "auto"

      • "standard_only"

    • speed: optional "standard" or "fast" or null

      Inference speed mode. fast provides significantly faster output token generation at premium pricing. Not all models support fast; invalid combinations are rejected at create time.

      • "standard"

      • "fast"

    • stop_sequences: optional array of string

      Custom text sequences that will cause the model to stop generating.

      Our models will normally stop when they have naturally completed their turn, which will result in a response stop_reason of "end_turn".

      If you want the model to stop generating when it encounters custom strings of text, you can use the stop_sequences parameter. If the model encounters one of the custom sequences, the response stop_reason value will be "stop_sequence" and the response stop_sequence value will contain the matched stop sequence.

    • stream: optional boolean

      Whether to incrementally stream the response using server-sent events.

      See streaming for details.

    • system: optional string or array of BetaTextBlockParam

      System prompt.

      A system prompt is a way of providing context and instructions to Claude, such as specifying a particular goal or role. See our guide to system prompts.

      • string

      • array of BetaTextBlockParam

        • type: "text"

        • text: string

          minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional array of BetaTextCitationParam or null

    • thinking: optional BetaThinkingConfigParam

      Configuration for enabling Claude's extended thinking.

      When enabled, responses include thinking content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your max_tokens limit.

      See extended thinking for details.

      • BetaThinkingConfigEnabled object

      • BetaThinkingConfigDisabled object

      • BetaThinkingConfigAdaptive object

    • tool_choice: optional BetaToolChoice

      How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

      • BetaToolChoiceAuto object

        The model will automatically decide whether to use tools.

        • type: "auto"

        • disable_parallel_tool_use: optional boolean

          Whether to disable parallel tool use.

          Defaults to false. If set to true, the model will output at most one tool use.

      • BetaToolChoiceAny object

        The model will use any available tools.

        • type: "any"

        • disable_parallel_tool_use: optional boolean

          Whether to disable parallel tool use.

          Defaults to false. If set to true, the model will output exactly one tool use.

      • BetaToolChoiceTool object

        The model will use the specified tool with tool_choice.name.

        • type: "tool"

        • name: string

          The name of the tool to use.

        • disable_parallel_tool_use: optional boolean

          Whether to disable parallel tool use.

          Defaults to false. If set to true, the model will output exactly one tool use.

      • BetaToolChoiceNone object

        The model will not be allowed to use tools.

        • type: "none"

    • tools: optional array of BetaToolUnion

      Definitions of tools that the model may use.

      If you include tools in your API request, the model may return tool_use content blocks that represent the model's use of those tools. You can then run those tools using the tool input generated by the model and then optionally return results back to the model using tool_result content blocks.

      There are two types of tools: client tools and server tools. The behavior described below applies to client tools. For server tools, see their individual documentation as each has its own behavior (e.g., the web search tool).

      Each tool definition includes:

      • name: Name of the tool.
      • description: Optional, but strongly-recommended description of the tool.
      • input_schema: JSON schema for the tool input shape that the model will produce in tool_use output content blocks.

      For example, if you defined tools as:

      [
        \{
          "name": "get_stock_price",
          "description": "Get the current stock price for a given ticker symbol.",
          "input_schema": \{
            "type": "object",
            "properties": \{
              "ticker": \{
                "type": "string",
                "description": "The stock ticker symbol, e.g. AAPL for Apple Inc."
              \}
            \},
            "required": ["ticker"]
          \}
        \}
      ]

      And then asked the model "What's the S&P 500 at today?", the model might produce tool_use content blocks in the response like this:

      [
        \{
          "type": "tool_use",
          "id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
          "name": "get_stock_price",
          "input": \{ "ticker": "^GSPC" \}
        \}
      ]

      You might then run your get_stock_price tool with \{"ticker": "^GSPC"\} as an input, and return the following back to the model in a subsequent user message:

      [
        \{
          "type": "tool_result",
          "tool_use_id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
          "content": "259.75 USD"
        \}
      ]

      Tools can be used for workflows that include running client-side tools and functions, or more generally whenever you want the model to produce a particular JSON structure of output.

      See our guide for more details.

      • BetaTool object

        • type: optional "custom" or null

        • input_schema: object

          JSON schema for this tool's input.

          This defines the shape of the input that your tool accepts and that the model will produce.

          • type: "object"

          • properties: optional map[unknown] or null

          • required: optional array of string or null

        • name: string

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

          maxLength: 128, minLength: 1, pattern: ^[a-zA-Z0-9_-]{1,128}$

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • description: optional string

          Description of what this tool does.

          Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

        • eager_input_streaming: optional boolean or null

          Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolBash20241022 object

        • type: "bash_20241022"

        • name: "bash"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolBash20250124 object

        • type: "bash_20250124"

        • name: "bash"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaCodeExecutionTool20250522 object

        • type: "code_execution_20250522"

        • name: "code_execution"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaCodeExecutionTool20250825 object

        • type: "code_execution_20250825"

        • name: "code_execution"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaCodeExecutionTool20260120 object

        Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

        • type: "code_execution_20260120"

        • name: "code_execution"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaCodeExecutionTool20260521 object

        Code execution tool with REPL state persistence.

        • type: "code_execution_20260521"

        • name: "code_execution"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaBrowserToolset20260801 object

        The browser toolset: a single tools[] entry (carrying no name) that declares the browser tool family. The model is served the family's tool with any members disabled via configs removed from its schema.

        • type: "browser_toolset_20260801"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • configs: optional BetaBrowserToolsetConfigs or null

          Per-member configuration for browser_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

          • type: optional BetaBrowserTypeConfig or null

            type's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • close_tab: optional BetaBrowserCloseTabConfig or null

            close_tab's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • double_click: optional BetaBrowserDoubleClickConfig or null

            double_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • file_upload: optional BetaBrowserFileUploadConfig or null

            file_upload's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • find: optional BetaBrowserFindConfig or null

            find's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • form_input: optional BetaBrowserFormInputConfig or null

            form_input's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • get_page_text: optional BetaBrowserGetPageTextConfig or null

            get_page_text's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • hold_key: optional BetaBrowserHoldKeyConfig or null

            hold_key's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • hover: optional BetaBrowserHoverConfig or null

            hover's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • javascript_exec: optional BetaBrowserJavascriptExecConfig or null

            javascript_exec's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • key: optional BetaBrowserKeyConfig or null

            key's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • left_click: optional BetaBrowserLeftClickConfig or null

            left_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • left_click_drag: optional BetaBrowserLeftClickDragConfig or null

            left_click_drag's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • left_mouse_down: optional BetaBrowserLeftMouseDownConfig or null

            left_mouse_down's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • left_mouse_up: optional BetaBrowserLeftMouseUpConfig or null

            left_mouse_up's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • list_tabs: optional BetaBrowserListTabsConfig or null

            list_tabs's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • middle_click: optional BetaBrowserMiddleClickConfig or null

            middle_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • mouse_move: optional BetaBrowserMouseMoveConfig or null

            mouse_move's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • navigate: optional BetaBrowserNavigateConfig or null

            navigate's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • new_tab: optional BetaBrowserNewTabConfig or null

            new_tab's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • read_console: optional BetaBrowserReadConsoleConfig or null

            read_console's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • read_network: optional BetaBrowserReadNetworkConfig or null

            read_network's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • read_page: optional BetaBrowserReadPageConfig or null

            read_page's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • right_click: optional BetaBrowserRightClickConfig or null

            right_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • screenshot: optional BetaBrowserScreenshotConfig or null

            screenshot's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • scroll: optional BetaBrowserScrollConfig or null

            scroll's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • scroll_to: optional BetaBrowserScrollToConfig or null

            scroll_to's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • switch_tab: optional BetaBrowserSwitchTabConfig or null

            switch_tab's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • triple_click: optional BetaBrowserTripleClickConfig or null

            triple_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • wait: optional BetaBrowserWaitConfig or null

            wait's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • zoom: optional BetaBrowserZoomConfig or null

            zoom's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • BetaToolComputerUse20241022 object

        • type: "computer_20241022"

        • display_height_px: number

          The height of the display in pixels.

          minimum: 1

        • display_width_px: number

          The width of the display in pixels.

          minimum: 1

        • name: "computer"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • display_number: optional number or null

          The X11 display number (e.g. 0, 1) for the display.

          minimum: 0

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaMemoryTool20250818 object

        • type: "memory_20250818"

        • name: "memory"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolComputerUse20250124 object

        • type: "computer_20250124"

        • display_height_px: number

          The height of the display in pixels.

          minimum: 1

        • display_width_px: number

          The width of the display in pixels.

          minimum: 1

        • name: "computer"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • display_number: optional number or null

          The X11 display number (e.g. 0, 1) for the display.

          minimum: 0

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolTextEditor20241022 object

        • type: "text_editor_20241022"

        • name: "str_replace_editor"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolComputerUse20251124 object

        • type: "computer_20251124"

        • display_height_px: number

          The height of the display in pixels.

          minimum: 1

        • display_width_px: number

          The width of the display in pixels.

          minimum: 1

        • name: "computer"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • display_number: optional number or null

          The X11 display number (e.g. 0, 1) for the display.

          minimum: 0

        • enable_zoom: optional boolean

          Whether to enable an action to take a zoomed-in screenshot of the screen.

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaComputerToolset20260801 object

        The computer toolset: a single tools[] entry (carrying no name) that declares the computer tool family. The model is served the family's tool with any members disabled via configs removed from its schema. Every member is enabled by default, zoom included. The single-tool options display_number and enable_zoom are not fields of a toolset entry — it carries only type, configs, and cache_control; zoom is controlled via configs.zoom.enabled.

        • type: "computer_toolset_20260801"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • configs: optional BetaComputerToolsetConfigs or null

          Per-member configuration for computer_toolset_20260801: one optional field per member tool, keyed by the member name — the same name the member's tool_use blocks carry. Every member is an accepted key, and a member's defaults apply wherever its key is absent. Unknown keys are rejected: the field set is this toolset version's complete member set.

          • type: optional BetaComputerTypeConfig or null

            type's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • cursor_position: optional BetaComputerCursorPositionConfig or null

            cursor_position's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • double_click: optional BetaComputerDoubleClickConfig or null

            double_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • hold_key: optional BetaComputerHoldKeyConfig or null

            hold_key's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • key: optional BetaComputerKeyConfig or null

            key's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • left_click: optional BetaComputerLeftClickConfig or null

            left_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • left_click_drag: optional BetaComputerLeftClickDragConfig or null

            left_click_drag's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • left_mouse_down: optional BetaComputerLeftMouseDownConfig or null

            left_mouse_down's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • left_mouse_up: optional BetaComputerLeftMouseUpConfig or null

            left_mouse_up's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • middle_click: optional BetaComputerMiddleClickConfig or null

            middle_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • mouse_move: optional BetaComputerMouseMoveConfig or null

            mouse_move's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • right_click: optional BetaComputerRightClickConfig or null

            right_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • screenshot: optional BetaComputerScreenshotConfig or null

            screenshot's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • scroll: optional BetaComputerScrollConfig or null

            scroll's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • triple_click: optional BetaComputerTripleClickConfig or null

            triple_click's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • wait: optional BetaComputerWaitConfig or null

            wait's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

          • zoom: optional BetaComputerZoomConfig or null

            zoom's config overrides.

            • defer_loading: optional boolean or null

              Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

            • enabled: optional boolean or null

              Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

      • BetaToolTextEditor20250124 object

        • type: "text_editor_20250124"

        • name: "str_replace_editor"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolTextEditor20250429 object

        • type: "text_editor_20250429"

        • name: "str_replace_based_edit_tool"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • input_examples: optional array of map[unknown]

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolTextEditor20250728 object

        • type: "text_editor_20250728"

        • name: "str_replace_based_edit_tool"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • input_examples: optional array of map[unknown]

        • max_characters: optional number or null

          Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

          minimum: 1

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaWebSearchTool20250305 object

        • type: "web_search_20250305"

        • name: "web_search"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • allowed_domains: optional array of string or null

          If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

        • blocked_domains: optional array of string or null

          If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • max_uses: optional number or null

          Maximum number of times the tool can be used in the API request.

          exclusiveMinimum: 0

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

        • user_location: optional BetaUserLocation or null

          Parameters for the user's location. Used to provide more relevant search results.

          • type: "approximate"

          • city: optional string or null

            The city of the user.

            maxLength: 255, minLength: 1

          • country: optional string or null

            The two letter ISO country code of the user.

            maxLength: 2, minLength: 2

          • region: optional string or null

            The region of the user.

            maxLength: 255, minLength: 1

          • timezone: optional string or null

            The IANA timezone of the user.

            maxLength: 255, minLength: 1

      • BetaWebFetchTool20250910 object

        • type: "web_fetch_20250910"

        • name: "web_fetch"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • allowed_domains: optional array of string or null

          List of domains to allow fetching from

        • blocked_domains: optional array of string or null

          List of domains to block fetching from

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

          Citations configuration for fetched documents. Citations are disabled by default.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • max_content_tokens: optional number or null

          Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

          exclusiveMinimum: 0

        • max_uses: optional number or null

          Maximum number of times the tool can be used in the API request.

          exclusiveMinimum: 0

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaWebSearchTool20260209 object

        • type: "web_search_20260209"

        • name: "web_search"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • allowed_domains: optional array of string or null

          If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

        • blocked_domains: optional array of string or null

          If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • max_uses: optional number or null

          Maximum number of times the tool can be used in the API request.

          exclusiveMinimum: 0

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

        • user_location: optional BetaUserLocation or null

          Parameters for the user's location. Used to provide more relevant search results.

      • BetaWebFetchTool20260209 object

        • type: "web_fetch_20260209"

        • name: "web_fetch"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • allowed_domains: optional array of string or null

          List of domains to allow fetching from

        • blocked_domains: optional array of string or null

          List of domains to block fetching from

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

          Citations configuration for fetched documents. Citations are disabled by default.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • max_content_tokens: optional number or null

          Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

          exclusiveMinimum: 0

        • max_uses: optional number or null

          Maximum number of times the tool can be used in the API request.

          exclusiveMinimum: 0

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaWebFetchTool20260309 object

        Web fetch tool with use_cache parameter for bypassing cached content.

        • type: "web_fetch_20260309"

        • name: "web_fetch"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • allowed_domains: optional array of string or null

          List of domains to allow fetching from

        • blocked_domains: optional array of string or null

          List of domains to block fetching from

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

          Citations configuration for fetched documents. Citations are disabled by default.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • max_content_tokens: optional number or null

          Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

          exclusiveMinimum: 0

        • max_uses: optional number or null

          Maximum number of times the tool can be used in the API request.

          exclusiveMinimum: 0

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

        • use_cache: optional boolean

          Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

      • BetaWebSearchTool20260318 object

        • type: "web_search_20260318"

        • name: "web_search"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • allowed_domains: optional array of string or null

          If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

        • blocked_domains: optional array of string or null

          If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • max_uses: optional number or null

          Maximum number of times the tool can be used in the API request.

          exclusiveMinimum: 0

        • response_inclusion: optional "full" or "excluded"

          How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

          • "full"

          • "excluded"

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

        • user_location: optional BetaUserLocation or null

          Parameters for the user's location. Used to provide more relevant search results.

      • BetaWebFetchTool20260318 object

        • type: "web_fetch_20260318"

        • name: "web_fetch"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • allowed_domains: optional array of string or null

          List of domains to allow fetching from

        • blocked_domains: optional array of string or null

          List of domains to block fetching from

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • citations: optional BetaCitationsConfigParam or null

          Citations configuration for fetched documents. Citations are disabled by default.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • max_content_tokens: optional number or null

          Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

          exclusiveMinimum: 0

        • max_uses: optional number or null

          Maximum number of times the tool can be used in the API request.

          exclusiveMinimum: 0

        • response_inclusion: optional "full" or "excluded"

          How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

          • "full"

          • "excluded"

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

        • use_cache: optional boolean

          Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

      • BetaAdvisorTool20260301 object

        • type: "advisor_20260301"

        • model: Model

          The model that will complete your prompt.

          See models for additional details and options.

        • name: "advisor"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • caching: optional BetaCacheControlEphemeral or null

          Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • max_tokens: optional number or null

          Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

          minimum: 1024

        • max_uses: optional number or null

          Maximum number of times the tool can be used in the API request.

          exclusiveMinimum: 0

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolSearchToolBm25_20251119 object

        • type: "tool_search_tool_bm25_20251119" or "tool_search_tool_bm25"

          • "tool_search_tool_bm25_20251119"

          • "tool_search_tool_bm25"

        • name: "tool_search_tool_bm25"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaToolSearchToolRegex20251119 object

        • type: "tool_search_tool_regex_20251119" or "tool_search_tool_regex"

          • "tool_search_tool_regex_20251119"

          • "tool_search_tool_regex"

        • name: "tool_search_tool_regex"

          Name of the tool.

          This is how the tool will be called by the model and in tool_use blocks.

        • allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

          • "direct"

          • "code_execution_20250825"

          • "code_execution_20260120"

          • "code_execution_20260521"

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • defer_loading: optional boolean

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        • strict: optional boolean

          When true, guarantees schema validation on tool names and inputs

      • BetaMCPToolset object

        Configuration for a group of tools from an MCP server.

        Allows configuring enabled status and defer_loading for all tools from an MCP server, with optional per-tool overrides.

        • type: "mcp_toolset"

        • mcp_server_name: string

          Name of the MCP server to configure tools for

          maxLength: 255, minLength: 1

        • cache_control: optional BetaCacheControlEphemeral or null

          Create a cache control breakpoint at this content block.

        • configs: optional map[BetaMCPToolConfig] or null

          Configuration overrides for specific tools, keyed by tool name

          • defer_loading: optional boolean

          • enabled: optional boolean

        • default_config: optional BetaMCPToolDefaultConfig

          Default configuration applied to all tools from this server

          • defer_loading: optional boolean

          • enabled: optional boolean

    • output_format: optional BetaJSONOutputFormat or null

      Deprecated

      Deprecated: Use output_config.format instead. See structured outputs

      A schema to specify Claude's output format in responses. This parameter will be removed in a future release.

    • temperature: optional number

      Deprecated: Deprecated. Models released after Claude Opus 4.6 do not support setting temperature. A value of 1.0 of will be accepted for backwards compatibility, all other values will be rejected with a 400 error.

      Amount of randomness injected into the response.

      Defaults to 1.0. Ranges from 0.0 to 1.0. Use temperature closer to 0.0 for analytical / multiple choice, and closer to 1.0 for creative and generative tasks.

      Note that even with temperature of 0.0, the results will not be fully deterministic.

      maximum: 1, minimum: 0

    • top_k: optional number

      Deprecated: Deprecated. Models released after Claude Opus 4.6 do not accept top_k; any value will be rejected with a 400 error.

      Only sample from the top K options for each subsequent token.

      Used to remove "long tail" low probability responses. Learn more technical details here.

      Recommended for advanced use cases only.

      minimum: 0

    • top_p: optional number

      Deprecated: Deprecated. Models released after Claude Opus 4.6 do not support setting top_p. A value >= 0.99 will be accepted for backwards compatibility, all other values will be rejected with a 400 error.

      Use nucleus sampling.

      In nucleus sampling, we compute the cumulative distribution over all the options for each subsequent token in decreasing probability order and cut it off once it reaches a particular probability specified by top_p.

      Recommended for advanced use cases only.

      maximum: 1, minimum: 0

Returns

• BetaMessageBatch object

  • type: "message_batch"

    Object type.

    For Message Batches, this is always "message_batch".

    default: message_batch

  • id: string

    Unique object identifier.

    The format and length of IDs may change over time.

  • archived_at: string or null

    RFC 3339 datetime string representing the time at which the Message Batch was archived and its results became unavailable.

    format: date-time

  • cancel_initiated_at: string or null

    RFC 3339 datetime string representing the time at which cancellation was initiated for the Message Batch. Specified only if cancellation was initiated.

    format: date-time

  • created_at: string

    RFC 3339 datetime string representing the time at which the Message Batch was created.

    format: date-time

  • ended_at: string or null

    RFC 3339 datetime string representing the time at which processing for the Message Batch ended. Specified only once processing ends.

    Processing ends when every request in a Message Batch has either succeeded, errored, canceled, or expired.

    format: date-time

  • expires_at: string

    RFC 3339 datetime string representing the time at which the Message Batch will expire and end processing, which is 24 hours after creation.

    format: date-time

  • processing_status: "in_progress" or "canceling" or "ended"

    Processing status of the Message Batch.

    • "in_progress"

    • "canceling"

    • "ended"

  • request_counts: BetaMessageBatchRequestCounts

    Tallies requests within the Message Batch, categorized by their status.

    Requests start as processing and move to one of the other statuses only once processing of the entire batch ends. The sum of all values always matches the total number of requests in the batch.

    • canceled: number

      Number of requests in the Message Batch that have been canceled.

      This is zero until processing of the entire Message Batch has ended.

      default: 0

    • errored: number

      Number of requests in the Message Batch that encountered an error.

      This is zero until processing of the entire Message Batch has ended.

      default: 0

    • expired: number

      Number of requests in the Message Batch that have expired.

      This is zero until processing of the entire Message Batch has ended.

      default: 0

    • processing: number

      Number of requests in the Message Batch that are processing.

      default: 0

    • succeeded: number

      Number of requests in the Message Batch that have completed successfully.

      This is zero until processing of the entire Message Batch has ended.

      default: 0

  • results_url: string or null

    URL to a .jsonl file containing the results of the Message Batch requests. Specified only once processing ends.

    Results in the file are not guaranteed to be in the same order as requests. Use the custom_id field to match results to requests.

Example

curl https://api.anthropic.com/v1/messages/batches \
    -H 'Content-Type: application/json' \
    -H 'anthropic-version: 2023-06-01' \
    -H 'anthropic-beta: message-batches-2024-09-24' \
    -H "X-Api-Key: $ANTHROPIC_API_KEY" \
    -d '{
          "requests": [
            {
              "custom_id": "my-custom-id-1",
              "params": {
                "max_tokens": 1024,
                "messages": [
                  {
                    "content": "Hello, world",
                    "role": "user"
                  }
                ],
                "model": "claude-opus-5"
              }
            }
          ]
        }'

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