🚨 Claude Fable 5 is live - Anthropic’s first Mythos-class model for general use.
The headline number from early testing: Stripe ran it on a 50M-line Ruby codebase and a 2-month migration was done in a day.
A few things worth knowing before you switch:
- Queries touching cybersecurity, bio/chemistry, or suspected model distillation fall back to Opus 4.8 automatically - Anthropic tuned the classifiers conservative on purpose, so expect some false positives
- Free on paid plans (Pro, Max, Team, Enterprise) through June 22 only - after that, usage credits required until capacity catches up
- API access is fully available today with no cutoff
Mythos 5 is the same model with cyber safeguards lifted, but restricted to Glasswing partners for now.
$10/M input, $50/M output - less than half of Mythos Preview pricing.
Claude Fable 5 is available everywhere today. Claude Mythos 5 is restricted to Glasswing partners until we expand our trusted access program.
anthropic.com/news/claude-fa…