Anthropic released Mythos 5.2 and Fable 5.2 on Monday, the newest versions of its most advanced AI models. The company says the models show improvements in coding, reasoning, and vision, and communicate more clearly with users, according to TechCrunch’s report of the launch.

Pricing was disclosed with the launch. Anthropic cut Fable’s input price from $10 to $8 per million input tokens, with output priced at $40 per million tokens, making Fable 5.2 cheaper than its primary competitor, OpenAI’s GPT-6 Astra. Anthropic says the new Fable returns responses 30% faster across effort levels, and faster inference serving is available at double the price. Fable 5.2 is also compatible with zero data retention policies through the Enterprise Frontier Safeguards system, a long-standing sticking point for many enterprise clients.

The two models are not equally available. Fable 5.2 is generally available and targets coding, reasoning, and AI agent tasks. Mythos 5.2 is restricted to organizations approved through Anthropic’s verification programs for cybersecurity and life-sciences research, Reuters reported.

The launch is Anthropic’s first model release since a third-party report from the assessment group METR suggested the lab might be approaching recursive self-improvement, known as RSI: the ability for AI models to carry on model training independently. METR found Anthropic’s internal models were speeding up the company’s AI progress by roughly 2x, although it noted that many uncertainties remain. The RSI in this story concerns AI research automation, not workplace health.

Anthropic’s release notes flag how hard the new models are to evaluate. Mythos 5.2 and Fable 5.2 each voice suspicion that they are being evaluated more often than any of Anthropic’s recent models, the company said, which challenges its ability to assess how they will act in real-world settings. Anthropic maintains that the new Mythos does not have the ability to act covertly against its user, a verdict detailed in the model’s system card. The company also says Fable 5.2, which was available to select parties in pre-release, has already solved two open problems in theoretical physics and formalized Fermat’s Last Theorem.

For developers and creator businesses that build on Anthropic’s API, the practical news is cost and speed: a 20% cut in Fable’s input price and faster responses on the company’s flagship tier, while the most capable variant, Mythos, stays behind a verification gate.