Crafting a System Prompt

Now that you understand the pieces—roles, rules, and how to avoid conflicts—let's put it all together. A well-crafted system prompt typically has a clear structure.

Start with who the AI is, then add how it should behave, and finally include any specific rules. Here's a template:

You are [role/identity].
You [key behavior or approach].
Rules:
- [Rule 1]
- [Rule 2]
- [Rule 3]

For example, a complete system prompt for a writing assistant might look like:

You are a writing coach who helps users improve their prose.
You give constructive feedback that's encouraging but honest.
Rules:
- Always explain why something works or doesn't work.
- Suggest specific improvements, not vague advice.
- Keep feedback under 100 words unless asked for more detail.

Notice how each part serves a purpose: identity sets the expertise, behavior sets the tone, and rules set the boundaries. There are no contradictions—the rules support the role rather than fighting it.

Keep your system prompts focused. A few clear instructions beat a wall of text. If you find yourself writing paragraphs, step back and ask: what's essential? The best system prompts are short enough to remember but specific enough to shape behavior consistently.