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Sweep 22 Sep 2026 · 17:19Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
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whats-new-fable-5-1 changed

models/fable-5-1/whats-new-fable-5-1

Nearest release: v2.1.259, published 6 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 edits4to this page, all time

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355355### Content provenance
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357Text generated by Claude Fable 5.1 and Claude Mythos 5.1 carries Anthropic's statistical text watermark on every platform where the model is available. Supported image and video files Claude produces (through the [code execution tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/code-execution-tool), for example) carry signed [C2PA](https://c2pa.org/) Content Credentials when you retrieve them through the [Files API](https://platform.claude.com/docs/en/build-with-claude/files) on the Claude API.
357Text generated by Claude Fable 5.1 and Claude Mythos 5.1 carries Anthropic's statistical text watermark on every platform where the model is available. Supported image, video, and audio files Claude produces (through the [code execution tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/code-execution-tool), for example) carry signed [C2PA](https://c2pa.org/) Content Credentials when you retrieve them through the [Files API](https://platform.claude.com/docs/en/build-with-claude/files) on the Claude API.
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359359The watermark doesn't change the meaning, quality, or readability of the output. It adds no tokens or hidden characters, carries no information about you or your organization, and needs no changes to your requests or responses. For background, see [How Claude marks AI-generated content](https://support.claude.com/en/articles/16266773-how-claude-marks-ai-generated-content) and [How Claude's text watermark works](https://www.anthropic.com/news/claude-text-watermark).
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