Claude Fable 5: How It Differs from Mythos and the Opus Family
Anthropic’s lineup got two new names recently — Claude Fable 5 and Claude Mythos 5 — sitting above an already-strong Opus tier (Opus 4.6, 4.7, and 4.8). The marketing pages don’t really tell you what to use when, and the API differences are significant enough that a naive model-string swap will break production code. This post is the guide I wish existed: what these models are, how they relate to each other, exactly what changes at the API level, what changes behaviorally, and how to decide which one your workload actually needs. ...