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Sweep 02 Oct 2026 · 18:55Z Build v2.1.288 509 read Stable v2.1.285 Latest v2.1.288 Next v2.1.288 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Or, for the Project Glasswing model with the same capabilities: changedmodels/fable-5-1/migration-guide

Nearest release: v2.1.285, published 2 hours before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

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First seen 1 Sep 2026 this site's first read of the page
Recorded edits11to this page, all time

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572572 ```
573573 </CodeGroup>
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575 See [Strict tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/strict-tool-use) and [Forcing tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/define-tools#forcing-tool-use). If you forced a tool only to get schema-conformant JSON, use [JSON outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs#json-outputs) (`output_config.format`) instead.
575 See [Strict tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/strict-tool-use) and [Forcing tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/define-tools#forcing-tool-use). If you forced a tool only to get schema-conformant JSON, use [JSON outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs#usage) (`output_config.format`) instead.
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577577 If your application, rather than the user, requires a specific tool call on the current turn of a multi-turn conversation, append a [mid-conversation system message](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages) after the latest `user` turn. Name the tool, say the call is required for this turn, and tell Claude to open its response with it. Because the message is appended rather than written into the top-level `system` prompt, earlier turns stay byte-identical and keep their [prompt cache](https://platform.claude.com/docs/en/build-with-claude/prompt-caching) hits:
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