Claude Fable won’t answer basic biology questions
Summary
Anthropic just released Claude Fable 5, calling it the most powerful AI model it has ever made widely available and praising its skills in biology, among others. But the model won't answer basic biology questions - the kind you'd expect a high schooler to handle. Instead, it hands off the query to the former flagship […]
Discussion on
Trending posts from X.
Introducing Claude Fable 5: a Mythos-class model that we’ve made safe for general use.
— Claude (@claudeai) June 9, 2026
Its capabilities exceed those of any model we’ve ever made generally available. pic.twitter.com/2AvmEjHIX8
Fable 5 is the biggest step up I’ve felt in our models since Opus 4.5 back in November. After 4.5 came out I uninstalled my IDE when I realized that I’d been doing 100% of my coding in a terminal for a few weeks. With Fable, it’s felt like Claude has stepped up from being a…
— Boris Cherny (@bcherny) June 9, 2026