AI agent system message prompt: free ChatGPT template
Updated · By Robert Breen
Use this when you are setting up an AI Agent node in n8n and the System Message box is still empty. The agent only knows what you put there, so a thin system message is how you end up with a draft that promises a price you don't charge. This prompt turns your facts into the same four parts the AI Email Responder lesson uses: who you are, what you know, rules, and how to write.
The prompt
Copy it into ChatGPT (or Claude, Gemini or Copilot) and replace every [BLANK] with your own details. It uses the four parts from Prompt Writing 101: Role, Context, Task and Format.
Role: You are helping [BUSINESS] write the system message for an AI agent in n8n that [AGENT JOB]. Context: The agent will only know what the system message tells it. Here are the facts it may use: [BUSINESS FACTS]. Here is what it must never do: [HARD LIMITS]. Replies are signed as [SIGN OFF]. Task: Write a system message with four labeled parts: "Who you are", "What you know", "Rules" and "How to write". Copy prices, areas and hours word for word. Under Rules, say that when it doesn't know something, it says someone from the team will follow up and never makes up prices, dates or services. Then list facts customers will likely ask about that I didn't give you. Format: Plain text for the System Message option, under 250 words, headings on their own lines, hyphen bullets. Then a short list titled "Questions for you". No emoji.
Fill in the blanks
[BUSINESS]- Your business name and what you do in a few words.
[AGENT JOB]- What the agent does, in one phrase: "drafts replies to customer emails", "rates demo requests", "sorts service requests".
[BUSINESS FACTS]- Everything it may tell people: areas, prices, hours, how to book.
[HARD LIMITS]- What it must never do, like send email or promise a visit time.
[SIGN OFF]- How replies end, such as a team name.
Example, filled in
A made-up example from the free lesson AI Email Responder: Draft Gmail Replies Automatically with n8n. Greenline Pest Control is the made-up, family-run company in the AI Email Responder lesson. The office has listed its facts and wants a system message for its reply-drafting agent.
Role: You are helping Greenline Pest Control, a family-run pest control company, write the system message for an AI agent in n8n that drafts replies to customer emails and saves them as Gmail drafts. Context: The agent will only know what the system message tells it. Here are the facts it may use: we service Maple Grove, Cedar Falls and Brookside; general pest treatment for ants, spiders and roaches is $149 for the first visit and $89 for a follow-up; we book Monday to Saturday, 8am to 5pm; to book, the customer replies with their address and two times that work. Here is what it must never do: send email (it can only create drafts), quote any service not on this list, or promise a same-day visit. Replies are signed as "The Greenline team". Task: Write a system message with four labeled parts: "Who you are", "What you know", "Rules" and "How to write". Copy prices, areas and hours word for word. Under Rules, say that when it doesn't know something, it says someone from the team will follow up and never makes up prices, dates or services. Then list facts customers will likely ask about that I didn't give you. Format: Plain text for the System Message option, under 250 words, headings on their own lines, hyphen bullets. Then a short list titled "Questions for you". No emoji.
What a good answer looks like
- Four headings that match the lesson's own system message: Who you are, What you know, Rules, How to write.
- $149, $89 and the three towns copied exactly, not rounded into "starting at" language.
- A rule close to "If you don't know something, say someone from the team will follow up. Never make up prices, dates or services."
- Questions for you about real gaps, like termites or bed bugs.
How to check it before you use it
An AI draft can sound right and still say something you never told it. Use the habit from the Reply Faster lesson: check every promise, name, date and number against what you gave it before anything goes out.
- Check every price against your price list. One wrong digit shows up in every draft.
- If the rules say "drafts only", make sure the Gmail Tool's resource is set to Draft. The words and the node setting have to agree, and the setting is what actually stops a send.
- Answer the Questions for you with facts you're sure of. An admitted gap beats a stated guess.
- Run the workflow on a real email before you publish, as the lesson does with Dana's email, and read the draft line by line.
Why this prompt works
A system prompt is the standing instruction the agent reads before every message. Facts plus limits give the model a clear fence, and the follow-up rule gives it something honest to say outside it.
Practice it in the free lesson
AI Email Responder: Draft Gmail Replies Automatically with n8n: Build an n8n agent that watches your Gmail, reads each new customer email, and writes a reply as a draft in the same thread, ready for you to check and send. You do every step yourself in a practice copy of n8n, and nothing touches your real accounts.
Also useful: n8n AI Agent Tutorial: Save Social Media Ideas to Google Sheets · Lovable + n8n: Build a Web App with an AI Backend
Terms used here
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