Claude Fable 5.2 and Mythos 5.2: faster, cheaper, and more capable
Anthropic shipped Claude Fable 5.2 and Mythos 5.2 roughly two months after the 5.1 generation. Both models are faster, cheaper to run, and post notably higher benchmark scores across coding, scientific research, and security research.
Fable 5.2 benchmark jumps
The numbers Anthropic published show significant gains over Fable 5.1:
- FrontierCode 2.0: 49.1% vs. 32.4% in 5.1
- Scientific research tasks: 74.6% vs. 52.6%
- Robotics simulations: 64.9% vs. 27.6%
Anthropic also demonstrated what Fable 5.2 can do at scale. One engineer assigned it to build an operating system from scratch. Over eight days, it coordinated more than 1,000 AI agents and produced a working OS that boots on a laptop. Anthropic also claims the model solved two previously open problems related to black holes and helped formalize the mathematical proof of Fermat’s Last Theorem in 30 hours.
Mythos 5.2: better at security research, still gated
Fable and Mythos share the same underlying model. Mythos runs with fewer safeguards for sensitive cybersecurity and biomedical research. On Anthropic’s CVE Rediscovery benchmark, Mythos 5.2 scored 89.6% against Mythos 5.1’s 78.3%.
Access to Mythos 5.2 is not open. You need approval through Anthropic’s cybersecurity or life sciences verification programs. Enterprise customers can reach its capabilities through Claude Security.
Pricing
Both models drop to $8 per million input tokens and $40 per million output tokens, down from $10 and $50. An optional fast mode generates tokens up to 2.5 times faster at twice the standard price. Response speed is up to 30% faster than the 5.1 generation without the fast mode add-on.
Fable 5.2 is available to standard Claude users and developers today. Mythos 5.2 remains restricted.
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