OpenAI Releases GPT-5.5 Prompting Guide
OpenAI has published a prompting guide for GPT-5.5, now available in the API. The guide recommends treating GPT-5.5 as a new model family rather than a drop-in replacement for GPT-5.2 or GPT-5.4, advising developers to start with a fresh baseline instead of carrying over existing prompts. A key tip for applications that spend time thinking before responding is to run an upgrade command in Codex that follows OpenAI's embedded advice. The upgrade guide includes instructions on rewriting prompts to fit the new model. The guide warns that existing prompts optimized for previous models may not work effectively with GPT-5.5. Simon Willison posted a link to the guide on April 25, 2026.
Key facts
- GPT-5.5 is now available in the API.
- OpenAI released a prompting guide for GPT-5.5.
- The guide recommends treating GPT-5.5 as a new model family.
- Developers should start with a fresh baseline, not carry over old prompts.
- A trick for long-thinking apps is to run an upgrade command in Codex.
- The upgrade guide includes instructions on rewriting prompts.
- Existing prompts for GPT-5.2 or GPT-5.4 may not work well.
- Simon Willison posted the link on April 25, 2026.
Entities
Institutions
- OpenAI