Anthropic Releases Claude Fable 5.1 and Mythos 5.1
Anthropic has launched new versions of its models, Claude Fable 5.1 and Mythos 5.1, featuring improved performance and reduced usage costs.
Anthropic Releases Claude Fable 5.1 and Mythos 5.1
Fable 5.1 is the new flagship model from Anthropic for all users. Mythos 5.1 is its version with relaxed cybersecurity and biology restrictions, available only to verified organizations.
Benchmarks
The update shows significant improvements:
- Terminal-Bench 4.0: 55.8%, with Mythos at 60.9%
- Terminal-Bench-Science: 52.6% compared to 24.7% in the previous version
- Humanity's Last Exam: 60.9% without tools and 65% with them
- OSWorld 2.0: 77.9%
Pricing and Costs
The price remains unchanged at $10/$50 per million tokens, but cache reads have decreased by 75% to $0.25 per million. According to Anthropic, this could reduce costs by about 25% in typical scenarios and up to 45% in agent-based scenarios.
At Low/Medium effort, Fable 5.1 can already produce results at the level of Fable 5 at a lower cost. In Claude Code, High is used by default, while in Cowork and claude.ai – Medium.
Cybersecurity
Additionally, cyber filters now trigger approximately 60% less frequently, and the model has been allowed to be used for vulnerability discovery, but not for writing exploits.
Why it matters
AnalysisThis is significant as the new versions of Anthropic's models offer improved performance and reduced costs, which can greatly impact the use of AI across various sectors.
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