Codex Prompting GuideCodex models advance the frontier of intelligence and efficiency and our recommended agentic coding model. Follow this guide closely to ensure you’re getting the best performance possible from this model. This guide is for anyone using the model directly via the API for maximum customizability; we also have the Codex SDK for simpler integrations. In the API, the Codex-tuned model is gpt-5.3-codex
