Apr 26, 2026
OpenAI has released a prompting guide for GPT-5.5 with one major takeaway: don't reuse your old prompts. Start fresh with minimal, result-focused instructions. And role definitions, once dismissed as outdated, are back at the top of OpenAI's prompt structure.
In its new prompting guide, OpenAI tells developers not to treat GPT-5.5 as a drop-in replacement for earlier models like GPT-5.2 or GPT-5.4. Migration should start from scratch with the smallest prompt that still gets the job done. Only then should developers tune reasoning effort, scope, tool descriptions, and output format using representative examples.
OpenAI says GPT-5.5 reasons more efficiently than its predecessors, so you should test the "low" and "medium" effort levels first before reaching for higher settings. Short, outcome-driven prompts tend to outperform process-heavy prompt stacks.
Old prompts can hold the model back
