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Sweep 28 Aug 2026 ยท 16:06Z Build v2.1.251 479 read Stable v2.1.236 Latest v2.1.251 Next v2.1.251 Feeds RSS JSON llms.txt

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

One change

introducing-claude-fable-5-and-claude-mythos-5

about-claude/models/introducing-claude-fable-5-and-claude-mythos-5

first seen The page's own history The capture it came from

Nearest release: v2.1.242, published an hour 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.

about-claude/models/introducing-claude-fable-5-and-claude-mythos-5 Page removed · 133 lines, page removed

## Models ## Refusals, fallback, and billing on Claude Fable 5 ### Refusals ### Fallback ### Billing ## Availability ## Working with Claude Fable 5 and Claude Mythos 5 ### Prompting ## Messages API on Claude Fable 5 and Claude Mythos 5 ### Adaptive thinking is always on ### Raw thinking content is never returned ## Supported features ## Migrating from earlier models ## Next steps

The page is gone upstream. What it last said is kept here.