Mythos 5

In depth

The uncapped sibling of Fable 5, announced by Anthropic on June 9, 2026 as the same underlying model with the safeguards lifted in some areas. Where Fable 5 wraps the weights in classifiers that route sensitive requests to Opus 4.8, Mythos 5 has those classifiers partially or fully removed depending on the access tier, and it stays behind a government-coordinated access program rather than shipping for general use. Both are Mythos-class, a tier above Opus, priced at $10 per million input and $50 per million output tokens.