Anthropic · Claude · Fable · Mythos

Claude Fable 5.1

Released 1 Sep 2026 · 39 days after Claude Opus 5

a new all-time high across the nine labsnotable release

+3.8 index over Fable 5.

Intelligence

#1 of 13 scored releases to that date

Price

$20.00

per 1M tokens, 3:1 in/out · $10 in / $50 out

Speed

output tokens/s, median

Weights

Closed

US lab

Anthropic’s best score over time