Anthropic's most advanced models: Fable 5.1 and Mythos 5.1, for coding and knowledge work
Anthropic released Fable 5.1, generally available on AWS, Google Cloud, Azure and the Claude apps, and Mythos 5.1 — the same model under stricter access controls, limited to vetted organizations via its Cyber and Life Sciences Verification Programs. Terminal-Bench 4.0 reaches 60.9% for Mythos 5.1 vs Fable 5's 42.0%, with pricing unchanged at $10/$50 per million tokens and cache reads down 75%.
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ANTHROPIC.COMClaude · Chronicle
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FAQWhat did Claude announce on SEP 01, 2026?
Anthropic released Fable 5.1, generally available on AWS, Google Cloud, Azure and the Claude apps, and Mythos 5.1 — the same model under stricter access controls, limited to vetted organizations via its Cyber and Life Sciences Verification Programs. Terminal-Bench 4.0 reaches 60.9% for Mythos 5.1 vs Fable 5's 42.0%, with pricing unchanged at $10/$50 per million tokens and cache reads down 75%.
What is Claude?
Claude pairs frontier reasoning with a careful, direct style — strong at writing, analysis, and code, with deep integrations across everyday work tools.
Where is the official source for this announcement?
It was published by Anthropic on SEP 01, 2026 via anthropic.com, the company's official channel. AgentMaps cites the primary source for every charted signal.