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Anthropic · First-party API · LLM

claude-fable-5-1

Release announcedReleased on Sep 1, 2026
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Notice

Release announced

Released on Sep 1, 2026

Anthropic announced this model on 2026-09-01.

Hosting route
First-party API
Affected scope
Not stated in the notice
Announced
Sep 1, 2026
First seen by ModelClock
Oct 3, 2026

What the provider published

platform.claude.com ↗
  • We've launched Claude Fable 5.1 (claude-fable-5-1), the successor to Claude Fable 5 for long-running agentic coding, knowledge work, and research, alongside Claude Mythos 5.1 (claude-mythos-5-1) for Project Glasswing participants.

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