OpenAI updates GPT-5.4 prompting guidance for more reliable agents

What OpenAI Developers posted on X

On March 6, 2026, OpenAI Developers said it had updated its GPT-5.4 prompting guide for API users. The X post framed the change around reliable agent patterns: tool use, structured outputs, verification loops, and long-running workflows. That is a notable shift in emphasis. OpenAI is not only telling developers what GPT-5.4 can do, but how to keep it consistent when tasks stretch across many steps and tool calls.

What the guide recommends

The documentation says GPT-5.4 is optimized for long-running task performance, stronger control over style and behavior, and more disciplined execution across complex workflows. OpenAI argues that teams get the best results when they define an output contract, tool-use expectations, and explicit completion criteria. The guide also highlights practical controls such as constraining verbosity, enforcing structured output, requiring grounding and citation rules, and telling the model how to recover when a retrieval step or subtask comes back incomplete.

Why it matters

The practical value is that prompt design is becoming part of production engineering rather than a lightweight experimentation step. A model that is strong in isolation can still fail in real deployments if it skips prerequisites, stops after partial coverage, or mishandles instruction changes mid-session. OpenAI’s updated guidance reads like operational advice for teams shipping agents into customer-facing or business-critical workflows, where reliability and predictable completion matter as much as raw reasoning quality.

That makes this update relevant beyond GPT-5.4 itself. It signals that the market is moving toward eval-driven prompt patterns, recovery rules, and explicit definitions of “done” as standard controls for agent systems. In other words, vendors are starting to document not only model capabilities, but the workflow discipline needed to turn those capabilities into dependable software.

Sources: OpenAI Developers X post, OpenAI API docs