Anthropic has released Claude Fable 5.1 for coding and knowledge work, alongside the more restricted Claude Mythos 5.1.
Base pricing for Fable remains $10 per million input tokens and $50 per million output tokens. The material change is cache-read pricing, which falls to $0.25 per million tokens. That matters most for agents that repeatedly reuse a large working context over long tasks.
Anthropic estimates the lower cache price can reduce typical billed workloads by about 25% and highly agentic workloads by as much as roughly 45%. Those are Anthropic’s own estimates, so actual savings will depend on workload structure and cache reuse.
Fable 5.1 is available to supported paid Claude users and through the Claude Platform and partner clouds. Mythos 5.1 uses the same underlying model with different safeguards and remains restricted to vetted cybersecurity and life-sciences use.