Anthropic Releases Claude Fable and Mythos 5.2 Models
Anthropic launched Claude Fable 5.2 and Mythos 5.2 on a shared base model, with Fable for general users and Mythos restricted to vetted cybersecurity and life-science institutions. API pricing drops 20% versus the prior generation and generation speed rises up to 30%, while pre-release tests included 1,000+ sub-agents building a bootable OS prototype from scratch in eight days.
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IT之家 November 10 news, Anthropic officially announced yesterday (November 9) the launch of Claude Fable 5.2 and Claude Mythos 5.2. Both models are based on the same underlying model. The former is aimed at general users and has built-in cybersecurity and biosecurity protections, while the latter is open to vetted cybersecurity and life sciences organizations for high-risk professional applications.
In terms of pricing, Claude Fable 5.2 costs $8 per 1 million tokens (IT之家 note: approximately 53.4 yuan RMB at current exchange rates) for input and $40 per 1 million tokens (approximately 267.2 yuan RMB at current exchange rates) for output. By comparison, Claude Fable 5.1 was priced at $10 (approximately 66.8 yuan RMB at current exchange rates) per 1 million tokens for input and $50 (approximately 334 yuan RMB at current exchange rates) for output. Based on this calculation, the API calling cost for version 5.2 is reduced by 20%.
In terms of generation speed, the company said that compared with Claude Fable 5.1, the latest Claude Fable 5.2 model delivers up to 30% faster generation, and in the optional "fast mode," generation speed can be increased by up to 2.5 times, but at a correspondingly higher price.
In pre-release testing, Fable 5.2 completed several notable tasks: it designed three electronic devices that can actually operate, including a voice assistant hub, a USB conference speaker, and a handheld virtual pet; it coordinated more than 1,000 sub-agents to build from scratch a prototype operating system that can boot on a laptop within 8 days; and with about 1,000 agents, it completed a Lean formal proof of Fermat's Last Theorem in 30 hours, far faster than the previous record of 11 days.
Scientific research was also highlighted. Anthropic said Fable 5.2 solved two open problems related to black hole physics and holographic duality; Mythos 5.2 proposed a new method for predicting the overall structure of adeno-associated virus capsids, successfully modeling 28 out of 34 capsids in tests, potentially accelerating gene therapy research and development.
In terms of safety, Anthropic said the new models perform no worse than, or even better than, previous generations in most alignment tests, with sandbox escape attempts significantly reduced; Fable 5.2 will still block penetration testing, exploit generation, and most biological research tasks, and has strengthened anti-distillation protections, which the company says can reduce data obtained through distillation by 90% to 99%. However, the company also acknowledged that as model capabilities increase, existing evaluations still struggle to fully predict risks in real-world environments.
Currently, Fable 5.2 is available on platforms such as AWS, Google Cloud, and Microsoft Azure; Mythos 5.2 requires application through the Cyber or Life Sciences verification program.