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291291Interleaved thinking lets Claude think between tool calls within a single assistant turn, reasoning about each tool result before deciding what to do next. For the concept, the turn structure, and how it behaves on adaptive-thinking models, see [interleaved thinking](https://platform.claude.com/docs/en/build-with-claude/thinking#interleaved-thinking) in the thinking overview. This section covers how to enable it when you use manual `type: "enabled"` thinking.
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293On Claude Opus 4.5, Claude Sonnet 4.5, and earlier Claude 4 models (Claude Opus 4.1, Claude Opus 4, and Claude Sonnet 4), add the `interleaved-thinking-2025-05-14` [beta header](https://platform.claude.com/docs/en/api/beta-headers) to your API request.
293On Claude Opus 4.5, Claude Sonnet 4.5, and earlier Claude 4 models, add the `interleaved-thinking-2025-05-14` [beta header](https://platform.claude.com/docs/en/api/beta-headers) to your API request.
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295295The 4.6 generation splits in manual mode:
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