Ethan Mollick reviews Claude 5 Fable, the first public Mythos-class model

Ethan Mollick tested Claude 5 Fable, the first Mythos-class model released to the public, and found it outperformed every other public model he has used by a considerable margin, running up to a dozen hours on multi-page specifications. In one Claude Code session it built an interactive isochrone map by spawning cheaper Claude Sonnet agents to research over 2,200 flights, rail schedules and road speeds, and in another it worked nine and a half hours to produce Concord, software for calibrating human and AI judgement.