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Claude Fable 5
Anthropic · Fable
Anthropic released Claude Fable 5 on June 9, 2026.
Claude Fable 5 is the Anthropic model launched on June 9, 2026 as its most capable model open to all customers, released alongside Claude Mythos 5 for Project Glasswing participants. It supports a 1M token context window by default, 128k max output tokens and always-on adaptive thinking, and uses the tokenizer introduced with Claude Opus 4.7. Fable 5 runs safety classifiers on requests and responses: a declined request returns a refusal stop reason, and an opt-in fallbacks parameter can re-run it on another model. It requires 30-day data retention and is not available under zero data retention. Access was restored on July 1, 2026 after a pause. Its successor is Claude Fable 5.1.
Claude Fable 5 at a glance
- Released
- API model id
claude-fable-5- Available on
- Claude APIAmazon BedrockClaude Platform on AWSGoogle Cloud
- Announcement
- platform.claude.com
What changed
Fable 5 opened Anthropic's Fable line, priced above Opus at $10 / $50 per million tokens. Adaptive thinking is the only thinking mode: disabling thinking, manual thinking budgets and assistant prefill all return an error, and thinking output is omitted by default.
It also added the refusal categories and the fallbacks parameter for requests its safety classifiers decline.
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Claude Fable 5 release timeline
The launch and every later Anthropic release that mentions Claude Fable 5, oldest first.
- Claude Fable 5 launch
Claude Fable 5 launch as a Mythos-class model safe for general use
Source: Claude Help Center Release Notes - Claude Opus 5 launch
Launched Claude Opus 5, a cost-effective model matching Claude Fable 5 capabilities at half the price.
Source: Claude Help Center Release Notes
Claude Fable 5 FAQ
When was Claude Fable 5 released?
Anthropic released Claude Fable 5 on June 9, 2026. The launch entry below links to the official announcement.
Where is Claude Fable 5 available?
Claude Fable 5 is available on Claude API, Amazon Bedrock, Claude Platform on AWS and Google Cloud. Later availability changes are listed under follow-up releases on this page.
What is the Claude Fable 5 API model id?
Use claude-fable-5 in Anthropic's API.
Other Anthropic models
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