What Anthropic released
Anthropic's post, dated November 9, 2026, introduces Claude Fable 5.2 and Claude Mythos 5.2. It states: "Claude Fable and Claude Mythos are the same underlying model. Fable has strong cybersecurity and biology safeguards to guard against misuse, which allows us to make it available to all users." Organizations can apply for Mythos through Anthropic's Life Sciences and Cyber Verification Programs.
The post says testers found the new models communicate more clearly than past Fable and Mythos versions. "They generate outputs up to 30% faster than Claude Fable 5.1 and Claude Mythos 5.1, and they're available at a lower price: $8 per million input tokens and $40 per million output tokens." Anthropic's Fable 5.1 documentation lists $10 and $50, which matches that comparison. "Fable 5.2 and Mythos 5.2 also come with an optional fast mode, which speeds up token generation by up to 2.5 times," priced at $16 input and $80 output per million tokens.
Where it is available
"Claude Fable 5.2 is available today on all platforms, including Amazon Web Services, Google Cloud, and Microsoft Azure. Developers can get started with claude-fable-5-2 on the Claude Platform." Docs list the API ID claude-fable-5-2 on Google Cloud and Microsoft Foundry, and a different ID on Amazon Bedrock: anthropic.claude-fable-5-2. Fast mode is available on Claude Code, the Claude Platform, Claude Models on Google Cloud, and Microsoft Foundry (Anthropic hosted); Mythos fast mode is only for Verification Program organizations.
A limited launch offer is described on the announcement and in Anthropic's help article "Claude Fable 5.2 launch offers," updated November 10, 2026. Plans and seats that include Fable get one to three Fable limit resets based on subscription length, expiring March 8, 2027 at 11:59 pm PT. On Pro plans and standard Team seats, Fable models are included for one week from November 9 through November 16, 2026 at 11:59 pm PT, up to 50% of weekly usage limits, plus one reset that expires at the end of that week. The help article says the offers are not on Free, some Enterprise seat types, or HIPAA-ready Enterprise plans. After the week, Fable on Pro returns to usage credits.
What Anthropic reports
Anthropic's table lists FrontierSWE v2 at 69.9% for Fable 5.2, against 62.3% for Opus 5.5 and 65.5% for GPT-6 Astra, at each model's highest available effort unless noted. Other rows in the same table include FrontierCode 2.0 at 49.1% for Fable 5.2 at Xhigh effort. These are vendor results, not independent tests.
On Fermat's Last Theorem, Anthropic writes that "a team of 1,000 Fable 5.2 agents fully formalized the theorem in just 30 hours, with minimal human intervention," compared with an earlier 11-day formalization by an unreleased research version. That is Anthropic's account of its own experiment. For everyday work, Anthropic still recommends starting with Claude Opus 5.5 and moving to Fable or Mythos for more ambitious tasks.
What it means for you
If you already use Fable 5.1 via the API, 5.2 is cheaper per token and, according to Anthropic, faster. Check the four breaking changes in Anthropic's "What's new" document before you switch production code, including prefix checks on thinking blocks. If you use Claude apps on a paid plan, read the launch-offer article for whether you have a week of included Fable or unused resets, and watch usage because Fable consumes limits faster than other Claude models.
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Sources & further reading
Based on the official documentation below. Features and access can change; check the provider before making a decision.
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