Claude Fable 5.1 doubles its science score, then nails the pelican test
Anthropic's Fable 5.1 claims a new standard for coding and long-running tasks, backed by a jump to 52.6% on Terminal-Bench-Science, up from 24.7% for Fable 5. Simon Willison's first test is more telling: at low and medium effort the model skipped reasoning entirely, while max effort burned 65,927 tokens, $1.83 and 13 minutes producing the best pelican he's seen from any Anthropic model. The cost cliff between those extremes is the real takeaway.