Claude Fable 5.2

Anthropic · Fable

Anthropic released Claude Fable 5.2 on November 9, 2026.

Claude Fable 5.2 is the Anthropic model launched on November 9, 2026, built for demanding reasoning and long-horizon agentic work. It has a 1M token context window, 128k max output tokens, and costs $8 USD per MTok input and $40 USD per MTok output. It is available on the Claude API, Claude Platform on AWS, Claude Models on Google Cloud (Anthropic managed), Claude in Amazon Bedrock, and Claude Models on Google Cloud (Google managed).

Claude Fable 5.2 at a glance

Released
API model id
claude-fable-5-2claude-mythos-5-2
Available on
Claude APIClaude Platform on AWSClaude Models on Google Cloud (Anthropic managed)Claude in Amazon BedrockClaude Models on Google Cloud (Google managed)
Previous model
Claude Fable 5 (June 9, 2026)
Announcement
platform.claude.com

What changed from Claude Fable 5

Claude Fable 5.2 enforces a prefix check for all accounts, rejecting requests that edit system prompts, tools, or earlier messages and then send thinking blocks from later turns with a 400 error. It requires migration from the older computer_20251124 toolset to computer_toolset_20260801, which is mandatory on all platforms except Amazon Bedrock. The model also introduces changes to handling approvals, code ownership, and long agentic turns compared to previous versions.

New to model names and version numbers? Read how AI labs version their models.

Claude Fable 5.2 release timeline

The launch and every later Anthropic release that mentions Claude Fable 5.2, oldest first.

Claude Fable 5.2 FAQ

When was Claude Fable 5.2 released?

Anthropic released Claude Fable 5.2 on November 9, 2026. The launch entry below links to the official announcement.

Where is Claude Fable 5.2 available?

Claude Fable 5.2 is available on Claude API, Claude Platform on AWS, Claude Models on Google Cloud (Anthropic managed), Claude in Amazon Bedrock and Claude Models on Google Cloud (Google managed). Later availability changes are listed under follow-up releases on this page.

What is the Claude Fable 5.2 API model id?

Use claude-fable-5-2 and claude-mythos-5-2 in Anthropic's API.

What came before Claude Fable 5.2?

Claude Fable 5.2 follows Claude Fable 5, released on June 9, 2026.

Other Anthropic models

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