Long-Horizon Terminal-Bench Shows Even Top LLM Agents Fail Most Multi-Step Tasks
The benchmark evaluates 46 stateful terminal tasks that require hundreds of interactions, grading agents with hidden verifiers that rebuild final artifacts. Across 21 leading models, the best—xAI’s Grok 4.5—solves only 13 of 46 tasks, and 29 tasks remain unsolved by any model, highlighting a huge gap in long‑horizon capability.