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Anthropic released Claude Fable 5.2 and Claude Mythos 5.2 on November 9, 2026, about two months after the 5.1 versions. Fable 5.2 is available to all users, while Mythos 5.2 is limited to vetted organizations. Anthropic says both generate output up to 30% faster than their predecessors and cost less, at $8 per million input tokens and $40 per million output tokens.
Key facts
- Release: Fable 5.2 launched November 9, 2026 on all platforms. Mythos 5.2 is restricted to approved programs.
- Price: $8 per million input tokens and $40 per million output tokens, down from $10 and $50, per The Next Web.
- Speed: up to 30% faster output. An optional fast mode is up to 2.5 times quicker and costs twice as much, according to TechCrunch.
- Benchmarks: Fable 5.2 scored 49.1% on FrontierCode 2.0, against 32.4% for Fable 5.1, per Digital Trends. These are Anthropic's own figures.
- Availability: Anthropic's platform, Amazon Web Services, Google Cloud and Microsoft Azure, per The Next Web.
What Anthropic claims
Both models share one underlying model. Fable carries safeguards around cybersecurity and biology, while Mythos has looser ones. MacRumors reports Fable 5.2 has about 55% fewer blocks than Fable 5.1. Mythos is accessible through Anthropic's Life Sciences and Cyber Verification Programs and through Claude Security on Enterprise plans.
Anthropic cites a long list of results from prerelease testing. The Verge quotes the company saying the models solved two open problems in black hole physics and formalized the proof of Fermat's Last Theorem in 30 hours. The Next Web adds that the proof effort used 1,000 Fable 5.2 agents. On robotics, Fable 5.2 scored 64.9% on the RoboDojo benchmark, up from 27.6%. Mythos 5.2 found 14.4% more known vulnerabilities than Mythos 5.1 on an internal test. All of these are company claims.
