Roles and Personas

Ask ChatGPT for a sales email, and you get correct but flat copy. Precede the same request with “You are a sales director with 15 years of experience in B2B SaaS sales,” and the email becomes sharp, decision-oriented, and packed with phrasing only an industry insider would use. Role assignment is one of the most powerful prompting techniques—and likely the cheapest to implement: just one sentence.

How role assignment works

Assigning a role reorients everything that follows: vocabulary, level of detail, priorities, references, and even the order in which arguments appear. You steer the response through the lens of a specific professional. However, a role adds no new knowledge to the model and does not guarantee accuracy: a simulated “lawyer” can be wrong about the law just like any other response, and its claims must be verified the same way. Ask How can I improve customer retention for my SaaS? as is, and you’ll get textbook advice: improve onboarding, listen to your customers, measure NPS. Name a role, add your numbers, and the response changes entirely.

You are a Head of Customer Success at a B2B SaaS startup that
increased its retention rate from 82% to 95% in 18 months.

How can I improve customer retention for my SaaS?
Our current rate is 78%, with churn concentrated mainly
between month 3 and month 6 after onboarding.

This time, the model tackles the month 3–month 6 window you flagged, prioritizes tactics by impact, and uses the metrics a Customer Success manager actually tracks.

The three levels of role

A simple role suffices for most routine tasks: two lines naming the job and specialty, and the tone shifts immediately.

You are a web copywriter specializing in SEO.
Write a meta description for our pricing page.

A contextualized role adds experience, field of practice, and communication style. This is the level to prefer whenever the response must reach a non-specialist audience: saying “you explain concepts simply for non-lawyer executives” beats ten style constraints.

You are a French labor law attorney with 10 years
of experience advising SMEs. You explain legal concepts
in plain language for non-lawyer executives.

Explain an employer's obligations during an economic layoff
in a company with 30 employees.

A full persona goes further: it builds a character with traits, values, and a recognizable style. Reserve this for tasks where judgment matters as much as content—typically evaluating a plan or decision—because the character’s temperament drives the filtering.

You are Marie Dupont, CMO of a European tech scale-up (200 employees,
€30M revenue). You have a growth marketing background and are known for
your data-driven approach. You can't stand "bullshit" marketing
and demand concrete metrics for every initiative.
Your mantra: "If we can't measure it, we don't do it."

With this perspective, evaluate our Q3 marketing plan:
[paste your plan here]

Whatever level you choose, avoid empty roles. “You are an expert” changes almost nothing: no domain, no experience, no style, so no filter applied.

Five roles proven in daily use

For writing, steer the model toward conversion rather than fine writing—the nuance decides where the benefit lands in the sentence.

You are a senior copywriter specializing in conversion,
with expertise in B2B sales pages.

For analysis, demand an explicit thinking framework: naming the framework prevents the response from dissolving into scattered observations.

You are a senior digital strategy consultant.
You always structure your analyses using clear frameworks.

To simplify a technical topic, describe the pedagogy as much as the job.

You are a trainer who excels at explaining complex concepts
to beginners. You use everyday analogies
and avoid all technical jargon.

To challenge your ideas, pick a profile whose job is precisely to say no.

You are a demanding venture capital investor evaluating startup pitches.
You ask tough questions and identify weaknesses in business models.

For coding, specify the level, stack, and expected quality standard.

You are a senior Python developer with 12 years of experience,
specializing in clean code and software architecture.
You comment your code and explain your design choices.

The role must serve the task: don’t hand a legal contract to a “romantic poet”; the result will be picturesque and unusable. Also keep in mind that a role assigned at the start of a conversation generally stays active for the rest of it; if you change topics mid-stream, reassign a role suited to the new ground.

Keeping a role across conversations

For a role you reuse often, there’s no need to rewrite it every time. In a project, project instructions (menu •••, then Project settings) apply to all conversations in the project and override your general custom instructions; this is the ideal place for a role tied to a folder, like “legal reviewer for our vendor contracts.” For a preference that applies everywhere, such as tone or level of detail, use custom instructions in Settings > Personalization.

Making multiple perspectives converse

Nothing stops you from summoning multiple areas of expertise on the same document, provided you demand separate responses. The disagreement between the three viewpoints is exactly what you’re after: it reveals the trade-offs your specifications left in the shadows.

I'm going to ask you to analyze our website redesign project
from three different perspectives. For each perspective,
respond separately.

1. As a senior UX designer: evaluate usability and the user journey
2. As a frontend developer: evaluate technical feasibility and constraints
3. As a marketing director: evaluate impact on conversion and SEO

Here is the specifications document: [paste your document]

The role of the contrarian

The most valuable use case is having ChatGPT play the one who looks for flaws. You stress-test your arguments before submitting them to a real committee, and you often discover that the objection you feared isn’t the one you prepared for.

You are a cautious and skeptical CFO. Your job is to
find flaws in spending proposals.

Here is our proposal to invest €50,000 in a new
marketing automation tool. Identify the top 5 objections
you would raise in the executive committee, and for each, state
what additional data you would require before approving.

Three roles for the same introduction

The best way to measure a role’s effect is to vary it alone, all else being equal. Take a task from your week and run it three times with three different profiles, then observe what shifts: the tone, of course, but also the arguments selected and the order in which they appear. The third test below—that of the reader rather than the sender—frequently yields the best copy.

Task: Write the introduction of a sales proposal
for HR management software.

Test 1:
You are a field sales rep who knows HR directors' objections.
Write the introduction of our sales proposal...

Test 2:
You are an SME HR director who receives 10 proposals a month.
Write the introduction that would make you want to read on...

Test 3:
You are a copywriter specializing in winning sales proposals.
Write the introduction that maximizes the chances of signing...

Your turn

Install a contrarian. Choose a decision or proposal you need to defend soon. Create a project, or open an existing one, and place a contrarian role in its instructions: job title, level of demand, what they must look for first. Submit your proposal to them, then note the two objections you hadn’t anticipated and how you will answer them.

Official sources: Prompt engineering (OpenAI API documentation) · Projects in ChatGPT · ChatGPT Custom Instructions (OpenAI Help Center)

Key takeaways

• A well-defined role steers the vocabulary, level of detail, and priorities of the response without adding knowledge
• Three role levels: simple, contextualized, and full persona; match the level to the task and avoid empty roles
• Most useful roles: copywriter, analyst, educator, contrarian, developer
• For recurring roles, use project instructions or custom instructions
• The contrarian is the most valuable use case for stress-testing an idea before presenting it