Claude Fable 5.1 changelog

Full Claude Platform available on Google Cloud (Anthropic managed)

Claude Models on Google Cloud (Anthropic managed) is generally available with US and Global endpoints. It gives Google Cloud customers the full Claude Platform feature set with Google Cloud IAM, billing and commitment drawdown. Fable 5.1, Opus 5.5, Sonnet 5.5 and Haiku 5.5 are available, and fast mode for Opus 5.5 costs $8 / $40 per million input and output tokens there.

Who is affected:

Teams that buy Claude through Google Cloud and want features that the Google-managed offering lacks.

What to do:

No action needed. Google Cloud customers who need same-day Claude API features can switch to the Anthropic-managed offering.

Claude Fable 5.1 released as the successor to Fable 5

Claude Fable 5.1 (and Claude Mythos 5.1 for Project Glasswing participants) launched at the same $10 / $50 per million tokens as Fable 5, with cache reads cut to $0.25 per million tokens.

Who is affected:

Teams using Claude Fable 5 on the API or in the Claude apps.

What to do:

Move from claude-fable-5 to claude-fable-5-1 after checking the tool_choice and thinking-block changes.

Claude Fable 5.1 available in GitHub Copilot, with data retention by default

Claude Fable 5.1 is available on Copilot Pro+, Max, Business and Enterprise. Unlike other Claude models in Copilot it requires data retention so Anthropic can run safety classifiers. Eligible enterprises can use zero data retention through the end of 2026.

Who is affected:

Copilot organizations with zero data retention requirements.

What to do:

Copilot admins: review the data retention terms before enabling the Fable 5.1 policy.