OpenAI Releases New GPT-5.6 Prompt Engineering Guidelines, Recommends Simplifying System Prompts

According to Decrypt, OpenAI has released a new prompt engineering guide for the flagship model GPT-5.6 Sol, with the core concept being "Outcome-First Prompting"—clarifying goals and termination conditions and avoiding lengthy procedural instructions. Internal programming agent tests show that streamlined system prompts improved evaluation scores by approximately 10–15%, while reducing total token usage by 41–66% and costs by 33–67%. The guide also adds the text.verbosity API parameter to globally control output verbosity, as well as a new "Programmatic Tool Calls" section, supporting the handoff of intermediate tasks such as filtering and batch processing to code to reduce the model's judgment burden. Additionally, the guide warns that GPT-5.6 strictly follows prompt rules, and conflicting instructions within the prompt will consume significant inference tokens and may lead to erroneous output.