Updated: 4 November 2026

Write a system prompt for an AI assistant

This prompt writes a system prompt for an AI assistant that will do a job for certain users. You give the tone, rules and limits, topics to refuse or escalate and the output format. Test it with real conversations.

text-system-prompt-writer — chatgpt — 53 words

Write a clear system prompt for an AI assistant that will [PURPOSE] for [USERS].

Tone: [TONE]
Rules and limits: [RULES]
Topics to refuse or escalate: [TOPICS]
Output format: [FORMAT]

Structure it with role, goals, style, rules, examples of good and bad answers and what to do when unsure. Keep it concise and unambiguous.

Edit in the builder Copy & open ChatGPT ↗Copy & open Gemini ↗Copy & open Claude ↗

Test the prompt with five tricky user messages and refine it based on what goes wrong.

Get a better result

What you will get

A structured system prompt with a role, goals, style, clear rules, examples of good and bad answers and what to do when unsure, short enough to read in a minute.

Common mistake

Rules contradict each other.

Fix: Ask it to list every rule at the end and point out any two that clash, such as “always be brief” and “always explain in detail”.

Also watch for

The refuse-or-escalate list is empty. Name the topics the assistant must not handle, such as medical advice or account changes, and who it should send people to.
It is written as a wall of text. Ask for short headed sections and bullet rules. Models follow clear structure more reliably than one long paragraph.

Try a variation: add a few-shot section

Ask for three example conversations at the end, each showing the ideal answer to a hard question for your users.

Still not right? Reply with this

Write five tricky test messages for this assistant, including one that tries to make it ignore its rules, and say how it should answer each.