Why a role changes the answer
Without a role, the model answers as a general assistant. It aims for the safe middle: a bit formal, a bit generic, useful but bland. When you give it a role, you point it at a narrower way of writing.
Ask it to act as a copy editor and it starts hunting for weak sentences. Ask it to act as a tutor and it slows down and explains. The facts do not change, but the shape of the answer does, and shape is often what you were missing.
A bare role vs a specific one
Bare role
“Act as an expert and review my resume.”
“Expert” at what? For whom? The model still has to guess.
Specific role
“Act as a hiring manager filling a junior developer role. Review this resume and flag the three weakest points a recruiter would notice first.”
Examples you can copy
Editing
"Act as a strict copy editor. Cut every sentence that does not earn its place, and tell me what you cut and why."
Learning
"Act as a patient tutor for a beginner. Explain this using one everyday example, then check my understanding with one question."
Coding
"Act as a senior developer doing code review. Point out bugs and risky patterns first, style last, and keep it short."
Feedback
"Act as a skeptical customer. Read this product description and tell me what would stop you from buying."
What a role cannot do
A role shapes how the model writes. It does not hand the model new facts. Telling it to “act as a doctor” does not make its medical claims safe to trust. It just makes them sound like a doctor.
So use roles to control tone, focus, and depth. Do not use them as a shortcut to expertise the model does not have. On anything that matters, still check the facts yourself.
More role prompts to copy
Here is a longer set you can adapt. Notice that the good ones do not just name a role; they add who the answer is for and what to focus on.
Marketing
"Act as a plain-spoken marketer. Rewrite this product blurb for busy small-business owners. Cut the buzzwords and lead with the benefit."
Job hunting
"Act as a hiring manager for a junior marketing role. Read my resume and tell me the three things that would make you skip it."
Studying
"Act as a patient tutor for a complete beginner. Explain this topic with one everyday example, then quiz me with two short questions."
Writing
"Act as a tough but fair editor. Cut anything that does not earn its place in this paragraph, and tell me what you cut and why."
Planning
"Act as a practical project planner. Turn this goal into a simple week-by-week plan with the riskiest step flagged."
Getting feedback
"Act as a skeptical first-time customer. Read this landing page and tell me what would stop you from buying."
A simple formula for writing your own
Once you see the pattern, you can build a role prompt for anything. The good ones have three parts, in this order.
Role + audience + focus. Name who the model should be, who the answer is for, and the one thing to focus on.
“Act as a [role] helping a [who the answer is for]. Focus on [the one thing that matters most].”
A bare “act as an expert” leaves the model guessing at all three. Filling in the blanks is what turns a vague role into a useful one.