During v3 testing for Fable 5.1 many of our requests were getting rejected due to Anthropic's safety guards misclassifying them as "reverse engineering" We were in contact with the Anthropic team the whole time and they tried to lift the restrictions in time for launch but ultimately we weren't able to finish testing. We're looking forward to getting this out when we finish it. TBD on when that is.

ARC Prize@arcprizeSep 1

Fable 5.1 from @AnthropicAI on ARC-AGI (Verified): - ARC-AGI-2: 90.0%, $3.12/task - ARC-AGI-1: 97.5%, $1.40/task Across the two benchmarks, Fable 5.1's average cost per task is about 32% lower than Fable 5's, driven by better token efficiency.