System Prompt Builder
Assemble a system prompt from role, tone, and constraints.
Inputs
System Prompt
Fill in a field to build your system prompt.
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About System Prompt Builder
The System Prompt Builder assembles a clear, structured system prompt from a few building blocks: the assistant's role, its tone, rules it must follow, the output format and examples. Structured instructions make chatbots and assistants behave more consistently.
How to use it
- Describe the role, for example "a helpful cooking assistant".
- Describe the tone, for example "friendly and concise".
- List constraints, one per line.
- Add an output format and examples if useful, then copy the finished system prompt.
Good to know
- The role becomes a "You are …" opening line, and constraints are formatted as a bulleted list.
- Every section is optional. Empty fields are simply left out.
- Specific, testable rules such as "answer in under 100 words" work better than vague ones such as "be brief".
Common questions
Which AI tools can use this?
Any assistant or API that accepts a system prompt or custom instructions, including most chat products and model APIs.
How many examples should I include?
One to three short examples of ideal responses are usually enough to show the pattern without making the prompt too long.