What Role Instructions Can and Cannot Do
Unit ID: PAW-M04-U00 Estimated active time: 15-20 minutes
The most over-used line in prompting
> You are an expert lawyer with 20 years of experience.
Lines like this are everywhere. They do something, and it is not what most people think.
What a role actually changes
A role instruction changes register: vocabulary, structure, what the answer treats as worth mentioning.
Ask for an explanation of a contract clause "for a first-year law student" and you get definitions and context. Ask "for a practising solicitor" and you get shorter sentences and assumed knowledge.
That is a real and useful difference. It is a difference in how the answer is written.
What a role does not change
A role does not add knowledge the tool does not have. It does not make the answer more accurate, and it does not make it verified.
"You are an expert" cannot make an invented case citation real. If anything it raises the risk, because expert-sounding output is harder to doubt.
Confidence and correctness are separate, and role instructions move only the first.
Prefer describing the reader
A more reliable instruction names the audience rather than the speaker.
Instead of:
> You are an experienced nurse educator.
try:
> Write for a nurse in their first month on a ward, who knows the terminology but not this policy.
The second is checkable — you can tell whether the output suits that reader. The first is not.
When a role is worth using
Role instructions earn their place when the *form* of expert output is what you want: the structure of a case note, the conventions of a design review, the ordering of a clinical handover.
Use them for form. Do not use them for authority.
Mini practice
Take one prompt with a role instruction in it.
Rewrite it to describe the reader instead of the speaker.
Compare the two outputs, and note which one you could review more easily.