Anthropic Releases Claude Fable 5.1 and Mythos 5.1: Lower Costs and Enhanced Privacy
TFenrir · reddit · 2026-09-02
Anthropic has released Claude Fable 5.1 and Claude Mythos 5.1. Both are based on the same model but differ in safeguards: Fable 5.1 is generally available, while Mythos 5.1 is restricted to trusted access programs for cybersecurity and life sciences.
Key Updates:
- Price: Fable 5.1 is estimated to cost 25% less than Fable 5 for typical workloads due to lower cache read pricing. For highly agentic workflows, savings can reach 45%.
- Data Retention: The new Enterprise Frontier Safeguards (EFS) store data entirely in customer-controlled cloud infrastructure, offering zero-retention privacy while maintaining defense against adversarial use.
- Safeguards: Reduced false positives, with a 60% reduction in false positives for cybersecurity use cases.
Related event: Anthropic Releases Fable 5.1 and Mythos 5.1 with 75% Cheaper Caching(174 posts)→
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