Fable 5.1 is the broadly available version, with safeguards that block some high-risk work in cybersecurity and scientific research. Mythos 5.1 has fewer of those restrictions, but...

Anthropic releases Claude Fable 5.1 broadly and Mythos 5.1 to vetted Project Glasswing users, with 1M token context and reduced cache costs.

Anthropic has cut a Fable 5.1 cache hit to just $0.25 on input, down from $1.00 for Fable 5. That's also just 2.5% of Fable's normal input-token price of $10, rather than the 10%…