Anthropic launched Claude Fable 5, a state-of-the-art general-use model with Mythos-class capabilities that exceed all previously available Claude models, showing exceptional performance in software engineering, knowledge work, vision, and scientific research.
Fable 5 includes safety classifiers that automatically route queries about cybersecurity, biology/chemistry, and model distillation to Claude Opus 4.8, triggering fallback in less than 5% of sessions, balancing capability release with risk mitigation.
Claude Mythos 5, the same underlying model with safeguards lifted, is deployed through Project Glasswing for cybersecurity professionals and will expand to biology researchers through a trusted access program, with demonstrated impact on infrastructure security and drug design acceleration.
Fable 5 demonstrates breakthrough autonomous capabilities—completing months of engineering work in days, conducting novel biological research independently, and solving complex long-horizon tasks with minimal human direction—while maintaining alignment levels comparable to earlier Claude models.
Both models are priced at $10 per million input tokens and $50 per million output tokens, with Fable 5 rolled out conservatively across subscription tiers through June 22 due to expected high demand.