GPT-5 Prompting Guide (cookbook.openai.com)

OpenAI has released a comprehensive prompting guide for GPT-5, their latest flagship model designed to excel in agentic tasks, coding, reasoning, and steerability. This guide aims to help developers unlock GPT-5’s full potential by sharing best practices for maximizing output quality, especially in complex workflows involving tool calls, instruction adherence, and task management. Key technical innovations include the Responses API, which maintains reasoning context between calls, significantly improving efficiency, latency, and performance in multi-step applications. GPT-5 is tailored for flexible agentic control—from autonomous decision-making in ambiguous situations to focused execution of well-defined tasks. Users can calibrate the model’s "agentic eagerness" by adjusting parameters like reasoning_effort, balancing thorough context gathering with response speed. The guide also highlights strategies for managing tool call budgets, setting clear stop conditions, and using “tool preamble” messages to boost clarity and user trust during interactive tasks. These features empower developers to optimize GPT-5 for diverse domains, including software engineering, where the model demonstrates unmatched coding capabilities in large codebases, frontend frameworks, and iterative app development with self-reflective planning. Overall, this guide not only enhances practical deployment of GPT-5 but also exemplifies the evolving role of foundation models as adaptable, controllable agents in AI-driven workflows. By blending advanced prompting techniques with the new Responses API, GPT-5 sets a new standard for integrating deep reasoning and tool use, heralding a more intelligent and efficient generation of AI assistants for real-world, agentic applications.