Anthropic cuts Fable 5's biology fallbacks by 85%

Anthropic updated Claude Fable 5's biology safeguards to substantially reduce false positives, cutting biology-related fallbacks to a weaker model by about 85% across its product surfaces. Users should see far fewer downgrades on everyday health and educational questions like interpreting lab results or understanding symptoms, and healthcare professionals get more clinical support. Fable 5 still falls back to Opus 5 for requests Anthropic classes as dual-use, including virology, toxicology, and molecular design, so it remains unusable for professional biology research and drug development. Anthropic says it plans to close that gap through trusted access pathways. The company notes Fable 5 can now outperform experts on some highly complex biological tasks, the exact capability that makes the classifier necessary.

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