Claude Fable 5.1 Remains Latest Publicly Listed Fable Model

A post circulating on X claimed that an unverified reference to Claude Fable 5.5 appeared in Azure-related configuration files, but no primary material confirms the model or its release plans.

No screenshot, filing or official documentation supports the alleged configuration entry. The latest publicly listed Fable model is Claude Fable 5.1, while Claude 5.5 announcements so far cover Opus, Sonnet and Haiku.

Claude Fable 5.1 and Claude Mythos 5.1 were introduced in September 2026. Fable 5.1 became generally available, while Mythos 5.1 was limited to trusted-access programs.

Fable 5.1 is available through Amazon Web Services, Google Cloud and Microsoft Azure. Its pricing is $10 per million input tokens and $50 per million output tokens, while cached input reads cost $0.25 per million tokens.

Microsoft Foundry lists claude-fable-5-1 with a 1 million-token context window and a maximum output of 128,000 tokens. The model is listed as a preview hosted on Anthropic infrastructure.

Microsoft’s hosting comparison places Fable and Mythos preview models under the “Hosted on Anthropic” option. Its Azure-hosted list includes Claude Opus 5.5, Claude Opus 5, Claude Sonnet 5.5 and Claude Haiku 5.5, but not Fable 5.5.

The Claude 5.5 rollout began with Claude Opus 5.5 on Sept. 22, followed by Claude Sonnet 5.5 on Sept. 28 and Claude Haiku 5.5 on Oct. 7. Anthropic described Opus 5.5 as the first model in the Claude 5.5 family.

The rollout provides a possible basis for speculation about a Fable 5.5, but does not establish that such a model exists. Anthropic’s public system-card index lists Fable 5.1, Mythos 5.1, Opus 5.5, Sonnet 5.5 and Haiku 5.5, with no Fable 5.5 entry.

The development follows TokenPost’s earlier coverage of Claude Sonnet 5.5’s rollout.