MEPX
Chapter 6 of 10All chapters
  1. 1What a prompt is doing
  2. 2Giving context
  3. 3Examples
  4. 4Multi-step problems
  5. 5Controlling format
  6. 6Roles and personas
  7. 7Iterating
  8. 8Evaluating prompts
  9. 9Prompt injection
  10. 10Folklore and limits

Chapter 6 of 10

Roles and personas

A style lever, honestly described.

What it does

Telling a model to act as a particular kind of expert shifts vocabulary, framing and assumptions. It can help, and it does not add knowledge the model lacks.

  • Useful for audience and register: explain this to a beginner.
  • It will not make an unreliable answer reliable.

System instructions

Persistent instructions set behaviour for a whole conversation or application. Keep them short, specific and free of contradictions, which accumulate quickly.