Designing the system prompt

The system prompt sets role, constraints, and refusals. It is followed more reliably than instructions buried in user content, so the load-bearing rules belong here.

What this lesson covers

• Separate durable rules from per-request input
• State constraints and refusals explicitly
• Keep it short enough to stay affordable per call

This lesson sits in Prompting That Holds Up, part of Building AI Apps with LLMs. It assumes what came before it and leads directly into the next lesson in the module.