What is Claude Fable 5 (Mythos)?
Claude Fable 5 is Anthropic's most capable widely released model, built for the most demanding reasoning and long-horizon agentic work. It introduces Anthropic's fifth-generation AI architecture designed for days-long autonomous execution and enterprise applications.
Key Features
1. Long-horizon autonomous execution
Fable 5 handles complex tasks that previous models could not sustain, executing coding and knowledge work tasks for extended periods without intervention.
2. Exceptional software engineering
During early testing, Stripe reported that Fable 5 compressed months of engineering into days.
3. State-of-the-art vision
The model can interpret scientific figures and reconstruct applications from screenshots.
4. Advanced knowledge work
Fable 5 excels in financial reasoning, document analysis, and problem-solving tasks.
5. Memory and long-context handling
It remains focused across millions of tokens while maintaining context.
6. Built-in safety classifiers
Special safeguards monitor cybersecurity and biological queries, redirecting sensitive requests appropriately.
Availability and Pricing
- Available on Enterprise plans
- Supports AWS, Google Cloud, and Microsoft Foundry
- $10 per million input tokens
- $50 per million output tokens