GPT-5.5 edges Claude Fable 5 on UC Berkeley's Agents' Last Exam benchmark
OpenAI's GPT-5.5, operating through the Codex agent framework, scored a 24% pass rate on the Agents' Last Exam (ALE), beating Fable 5 at 22%. Built by UC Berkeley's Center for Responsible, Decentralized Intelligence with more than 300 domain experts, ALE tests real long-horizon professional workflows — 3D modeling in Siemens NX, scene setup in Unreal Engine, neuroimaging analysis in FSLeyes — rather than academic datasets. All frontier models scored below 25%.
why it mattersALE was designed to resist contamination; its sub-25% ceiling is the most honest current measure of where agentic AI actually stands on economically meaningful professional tasks.