Quiz 1: Plugin Fundamentals

Test your understanding of plugins, their anatomy, and how they differ across platforms.

Question 1: What is a plugin?

选项

• A. A plugin is a single reusable workflow, like calculating ROI
• B. A plugin is a collection of tools that provides standardized access to external APIs
• C. A plugin is a reusable extension surface; Claude Code and Codex use plugin bundles, while OpenCode plugins are code modules loaded from files or npm
• D. A plugin is a text file that describes how to use an agent tool

答案解析

• A — That's a skill, not a plugin. A plugin is the larger extension surface around reusable behavior.
• B — That's an MCP server. Plugins are a broader extension surface than MCP alone.
• C（正确答案） — Correct! The exact shape depends on the platform. Claude Code and Codex are manifest-first, while OpenCode plugins are code-first.
• D — That sounds like documentation, not a plugin. Plugins are actual packages with executable components.

Question 2: What does plugin.json do?

选项

• A. For Claude Code and Codex, plugin.json tells the agent the plugin's identity and where to find bundled components
• B. plugin.json is just documentation describing what's in the plugin
• C. plugin.json is a list of all the API endpoints the plugin can access
• D. plugin.json is automatically generated and doesn't need to be written manually

答案解析

• A（正确答案） — Correct! On manifest-first platforms, plugin.json identifies the plugin and points to skills, MCP config, or app integrations. OpenCode does not use this manifest model.
• B — It's more than documentation — it's structured metadata that agents parse to discover and load plugin components.
• C — No, that would be part of an MCP server definition or app integration config, not the plugin manifest.
• D — You write the manifest to define your plugin's identity. Some tools (like Codex's $plugin-creator) can scaffold it for you, but the file still matters.

Question 3: How do manifest-first plugins differ by platform?

选项

• A. Claude Code uses .claude-plugin/plugin.json; Codex uses .codex-plugin/plugin.json; both place skills/ at the plugin root
• B. All platforms use the exact same manifest.json format at the plugin root
• C. Only Codex supports plugin marketplaces
• D. Claude Code and Codex plugins are fully interchangeable

答案解析

• A（正确答案） — Correct! Both platforms use a similar pattern (manifest in a hidden directory, skills at root) but with platform-specific directory names.
• B — False. Claude Code uses .claude-plugin/plugin.json, Codex uses .codex-plugin/plugin.json. The schemas also differ.
• C — False. Both Claude Code and Codex support marketplace distribution. Claude Code uses the Anthropic marketplace; Codex uses .agents/plugins/marketplace.json.
• D — Not directly. While both can bundle skills and MCP servers, the manifest schemas and installation mechanisms differ.

Question 4: How do skills and MCP servers fit inside a plugin?

选项

• A. In Claude Code and Codex, a plugin can only contain skills OR MCP servers, not both
• B. In Claude Code and Codex, skills are human-readable workflows; MCP servers provide programmatic tool access
• C. Skills and MCP servers do the same thing; you only need one
• D. Only Claude Code plugins use skills; Codex plugins only use MCP servers

答案解析

• A — False. Manifest-first plugins can combine skills, MCP servers, and other components.
• B（正确答案） — Correct! Skills describe how to accomplish tasks; MCP servers provide standardized tool interfaces for agents to call.
• C — False. Skills describe how to do something; MCP servers provide what you can do — they're complementary.
• D — False. Both platforms support skills. Codex also supports MCP servers and app integrations.

Question 5: What can a Codex plugin reference?

选项

• A. The plugin manifest directory is always named .claude-plugin/ regardless of platform
• B. Codex plugins can reference MCP servers and app integrations via paths in plugin.json
• C. OpenCode uses a formal plugin manifest like Claude Code and Codex
• D. All plugins must have an MCP server to be useful

答案解析

• A — False. Claude Code uses .claude-plugin/, Codex uses .codex-plugin/. Each platform has its own directory name.
• B（正确答案） — Correct! Codex plugin.json uses fields like 'mcpServers': './.mcp.json' and 'apps': './.app.json' to reference bundled configuration files.
• C — False. OpenCode has native plugins, but they are JS/TS modules loaded from .opencode/plugins/ or npm packages listed in opencode.json, not manifest directories like .claude-plugin/ or .codex-plugin/.
• D — False. A plugin can contain just skills, or just configuration — MCP servers are optional.

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Summary

If you got 4-5 correct, you have a solid grasp of plugin anatomy. If you missed several, reread the introduction and anatomy lessons before moving on.

Key Takeaways

• Plugins are a packaging surface, not the same thing as a skill or an MCP server
• Claude Code and Codex use manifest-first plugins, while OpenCode uses code-first modules
• On manifest-first platforms, plugin.json tells the agent where bundled components live

Next Steps

Next, use plugins in a real workflow and see how installation and activation differ by platform.