How to use the System Prompt Generator
- 1. Describe the assistantGive it a name, a goal and the people it will talk to.
- 2. Add rules and factsList the facts it may rely on and what it must always and never do.
- 3. Generate and testCopy the system prompt into your app, then test it with tricky questions.
What a system prompt does
A system prompt is the standing instruction a model sees before every user message. In an API it's the system message; in ChatGPT it's the instructions of a custom GPT; in Gemini, a Gem; in Claude, project instructions. It shapes tone, scope and behaviour across every conversation, so it pays to write it carefully.
The generator uses short Markdown sections (Role, Goal, Tone and language, Facts, Always, Never, When unsure, Format), which models follow reliably and people can easily edit.
Worked example
The default example is CourseBuddy, an assistant for a coding institute that answers students and parents about schedules, fees, syllabus and enrolment. It has two facts (batches start on the first Monday of each month; classes run online and offline), two always rules, two never rules (no job or salary promises; no made-up fees or dates), a hand-off to the admissions team and the safety rules switched on. The result is a 202-word system prompt of about 288 tokens. Because it's sent with every conversation, that's roughly 288 extra input tokens per request, which you can price with our LLM API pricing calculator.
Tips
- Give the facts the assistant may use, and tell it to treat them as the only source for prices and dates. This is the simplest guard against made-up details.
- Write "never" rules for the mistakes that would hurt most, such as promising outcomes or giving medical advice.
- Test with questions it should refuse or hand off, and with users trying to override the rules.
- A system prompt guides behaviour but isn't a security boundary. Keep secrets and access control in your code, not in the prompt.
Frequently asked questions
Which format is best: Markdown or XML tags?
Both work with current models. This tool uses Markdown headings because they're easy for people to read and edit.
Can I use it for WhatsApp or website bots?
Yes. Paste the output as the system or instruction text in whichever AI API or bot platform you use.
Is the system prompt generator free?
Yes. You can open the system prompt generator and fill in everything without signing up. When you generate a prompt for the first time, we ask once for your name and WhatsApp number; after that it, and every other Uncodemy tool, opens straight away.