Anthropic has released Claude Fable 5.2 and Claude Mythos 5.2 for engineers and research teams that need more capacity than Claude Opus 5.5 on long coding, reasoning, and vision jobs. The two names are one underlying model. Fable 5.2 keeps cybersecurity and biology safeguards so Anthropic can offer it broadly, and it is available today on Anthropic's platforms, including Amazon Web Services, Google Cloud, and Microsoft Azure. Mythos 5.2 is the same model without those blocks, and only organizations approved through Anthropic's Cyber and Life Sciences Verification Programs can use it. The 5.2 models generate output up to 30% faster than the 5.1 versions from September, at $8 per million input tokens and $40 per million output tokens, down from $10 and $50. An optional fast mode runs up to 2.5 times quicker, at $16 and $80. Anthropic says prerelease testing included software migrations that had been impractical, three working electronic devices designed from scratch, solutions to two open problems in black hole physics, progress on robotics evaluations, and a formalization of the proof of Fermat's Last Theorem finished in 30 hours by about 1,000 agents. On the company's published benchmarks, Fable 5.2 scores 49.1% on FrontierCode 2.0 and 74.6% on Terminal-Bench-Science 0.1, ahead of Opus 5.5 on most of the tasks it measured. Anthropic still tells customers to start everyday coding and knowledge work on Claude Opus 5.5, and to move to Fable 5.2 when that model falls short on long agent jobs and hard technical problems. Testers found the 5.2 models clearer in how they communicate than earlier Fable and Mythos releases, and Anthropic says Fable 5.2 erroneously blocks safe prompts about 55% less often than Fable 5.1.