OpenAI released GPT-5.6 with three models: Sol, Terra, and Luna. Sol scored 53.6 on Agents' Last Exam, beating Claude Fable 5 by 13.1 points at about a quarter of the cost. Terra and Luna also outperform Fable 5 at much lower cost.

Sol scored 80.0 on the Artificial Analysis Coding Agent index, surpassing Claude Fable 5's 77.2. It uses less than half the tokens, runs twice as fast, and costs a third less. Ultra mode runs multiple agents in parallel for faster results.

GPT-5.6 can visually check rendered outputs, spotting and fixing errors before delivery. It produces cleaner presentations, documents, and tables with template support and exports to common tools.

ChatGPT Work launched as an agent inside.