Free Custom GPT Instructions Generator
Describe the assistant you want and generate clear, structured system instructions for a Custom GPT, a Claude Project or a Gemini Gem — role, rules, tone and output format included.
Your prompt
How to use the Custom GPT Instructions Generator
- Describe what the assistant should do and who it is for.
- Pick your platform — Custom GPT, Claude Project or Gemini Gem.
- Add a persona, tone and any hard rules it must follow.
- Click Generate Prompt, then paste the result into the instructions field.
Give your assistant a clear brief
A Custom GPT or Claude Project is only as good as its instructions. Vague setup — "be a helpful assistant" — produces vague, inconsistent answers. This generator turns your intent into a structured system prompt: a defined role, a tone, explicit do's and don'ts, a process for handling requests, and a fixed output format.
That structure is what makes an assistant behave predictably across hundreds of conversations. It knows when to ask a clarifying question, what it's not allowed to say, and exactly how to format a reply — so you get the same quality every time instead of rerolling.
Works across platforms
The same building blocks power Custom GPTs in ChatGPT, Projects in Claude and Gems in Gemini. Pick your platform and the instructions are shaped to fit, then refine them as you see how the assistant responds to real prompts.