Anthropic today introduced Claude Fable 5.2 and Claude Mythos 5.2, new versions of its Claude models with improvements in coding, reasoning and vision and outputs generated up to 30 percent faster than the 5.1 versions.
Both models are described as communicating more clearly than their 5.1 predecessors. Anthropic says Fable 5.2 also uses fewer tokens than Fable 5.1 on challenging tasks when set to medium effort.
Fable 5.2: availability, safeguards and performance
Fable 5.2 is available today on all platforms. The public-facing Fable 5.2 includes cybersecurity and biology safeguards intended to prevent misuse; compared with Fable 5.1 it has approximately 55 percent fewer blocks. Subscribers on eligible paid plans receive extra Fable usage this week, with one to three Fable resets depending on subscription length. Fable counts for up to 50 percent of weekly usage limits for Pro plans and standard seats on the Team plan.
Anthropic additionally offers a fast mode that speeds token generation by up to 2.5 times on Claude Code, the Claude Platform, Claude Models on Google Cloud, and Microsoft Foundry.
Both Fable 5.2 and Mythos 5.2 use the same underlying model, but Mythos does not carry the same public-facing limitations as Fable. Mythos is available through Anthropic’s Life Sciences and Cyber Verification Programs and via Claude Security on Enterprise plans.
Anthropic positions Fable and Mythos as suitable for “the most ambitious, open-ended technical work.” The company recommends starting with Opus 5.5 for most coding and knowledge tasks, then moving to a model such as Fable or Mythos for more complex requests, or stepping down to more affordable models like Sonnet or Haiku 5.5.
Benchmarks cited by Anthropic indicate that Fable and Mythos 5.2 outperform Opus 5.5 on a range of tasks, including computer use, knowledge work, cybersecurity, agentic scientific research, agentic coding and multidisciplinary reasoning.
