Model-specific guidance
Each of these models has its own prompting page. Read the one for your model first, then the techniques that follow.
| Model | Guide | What's different |
|---|---|---|
| Claude Fable 5.1 and Claude Mythos 5.1 | Prompting Claude Fable 5.1 | Differences from Claude Fable 5: effort levels, finishing long tasks, user-facing progress updates, passing thinking blocks back unchanged, tool-call batching in agent loops, search triggering at low effort, formatting, and writing density. |
| Claude Fable 5 and Claude Mythos 5 | Prompting Claude Fable 5 | Differences from Claude Opus 4.8: effort levels, instruction following, long-run progress claims, memory systems, and the reasoning_extraction refusal category. |
| Claude Sonnet 5 | Prompting Claude Sonnet 5 | Differences from Claude Sonnet 4.6: response length, effort and thinking-depth calibration, tool use triggering, literal instruction following, and design and frontend defaults. |
| Claude Opus 5 | Prompting Claude Opus 5 | Differences from prior Opus models: response length and verbosity, user-facing progress updates, written deliverable length, task scope and over-verification, subagent control, and self-correction. |
| Claude Opus 4.8 | Prompting Claude Opus 4.8 | Response length, effort and thinking-depth calibration, tool use triggering, literal instruction following, subagent control, and design and frontend defaults. |