GPT-5.5 is here! Available in the API, Codex and ChatGPT today
OpenAI Developer Community
April 28, 2026
Models gpt-5.x, as evaluated by ChatGPT itself, although very expensive, are hopeless in strict tasks like legal assistants. I found they hallucinate a lot and aren’t capable of sticking to the strict instructions and to the custom KB. Nor do gpt-4x models do it much better.
Discussion in the ATmosphere