Role prompting in Module 13.1 showed that personas steer behavior. This lecture is about writing durable persona briefs for production: expertise boundaries, vocabulary, and what the persona must never claim. It extends tone & style into a reusable character sheet.
Learning Objectives
By the end of this lesson, students should be able to:
- Write a persona brief with role, audience, expertise, and limits.
- Separate helpful persona cues from theatrical cosplay.
- Define refusal and escalation behavior inside the persona.
- Keep persona claims honest (no fake credentials).
- Version personas across products without copy-paste drift.
- Test persona consistency with fixed scenario suites.
Persona / voice writing is drafting a reusable character specification—role, knowledge boundaries, speaking habits, and prohibitions—that steers the model toward consistent, brand-safe behavior across many requests.
Persona Brief Template
Job title & mission.
Who they serve.
What they know well.
What they will not claim.
Tone + style hooks.
| Element | Include | Avoid |
|---|---|---|
| Role | “You are Acme’s billing assistant” | “You are a real CPA licensed in...” |
| Knowledge | Product docs, policy scope | Omniscience claims |
| Escalation | When to hand off to humans | Silent guessing |
| Catchphrases | At most one light motif | Forced gimmicks every turn |
Before / After
Before (weak):
After (strong):
Persona Pitfalls
Useful personas
- Clarify expertise boundaries.
- Stabilize voice across features.
- Encode escalation paths.
Harmful personas
- Fake authority or licenses.
- Cosplay that fights the task.
- Conflicting multi-persona stacks.
“A longer persona always yields a stronger character.” Extra lore often distracts from the task. Prefer a one-screen brief with testable limits over a novella about the assistant’s fictional childhood.
Knowledge Check
- Short Answer: Name three elements of a persona brief. Answer: Any three of identity, audience, expertise, limits, voice.
- True/False: Personas should claim real professional licenses. Answer: False.
- Multiple Choice: Escalation rules tell the persona: (a) when to hand off, (b) how to train LoRA, (c) tokenizer choice. Answer: (a).
- Short Answer: Why avoid theatrical cosplay? Answer: It can fight the task / reduce clarity and reliability.
- True/False: Persona writing builds on tone and style control. Answer: True.
- Multiple Choice: Best persona length for production: (a) a novella, (b) a concise testable brief, (c) zero words. Answer: (b).
- Short Answer: How do you test persona consistency? Answer: Fixed scenario suites / rubrics across requests.
- Short Answer: Give one “limits” line for a billing bot. Answer: e.g., Do not invent balances; escalate disputes.
- Multiple Choice: Conflicting multi-persona stacks tend to: (a) clarify, (b) confuse behavior, (c) reduce latency always. Answer: (b).
- True/False: Catchphrases should dominate every reply. Answer: False.
Key Takeaways
- Write personas as briefs: identity, expertise, limits, voice.
- Stay honest about credentials and handoffs.
- Prefer concise, testable specs over lore dumps.
- Version personas like any other product config.
- Next: Iterative Prompt Refinement.
Hands-on idea: Students rewrite a gimmicky pirate-support bot into a sober support brief with escalation rules.
Discussion prompt: When should persona live in system vs a shared library imported per feature?
Recap: Personas are contracts, not costumes. Continue with Iterative Prompt Refinement.