Key facts
- OpenAI's new GPT-5.6 Sol prompting guide emphasizes outcome-first prompting.
- Leaner system prompts improved coding agent evaluation scores by 10-15% in internal tests.
- The new guidelines reduce the need for extensive system prompts, style rules, and examples.
- GPT-5.6's reasoning tokens are consumed when reconciling conflicting rules, leading to slower and more expensive outputs.
- New features include the text.verbosity parameter and Programmatic Tool Calling.
OpenAI has introduced a new prompting guide for its latest flagship model, GPT-5.6 Sol, which marks a significant shift from previous advice. The core message is to reduce the length and complexity of system prompts, adopting an 'outcome-first' approach. This means defining the desired outcome, setting stopping conditions, and allowing the model to execute without excessive instruction.
Internal testing by OpenAI demonstrated that leaner system prompts led to an improvement in evaluation scores of approximately 10-15% for coding agents. Furthermore, this approach resulted in a substantial reduction in token usage, between 41-66%, and a corresponding decrease in costs, ranging from 33-67%.