Write the brief before the prompt
“Write a follow-up email” leaves the recipient, purpose, facts, and next step open. A more complete brief might say that the email follows a meeting, should confirm an agreed action, and must use only the notes you provide.
The extra information gives you a better way to assess the draft. You can compare it with a defined task instead of deciding whether it sounds convincing.
Include the audience, the source material, and the shape of the answer. Add examples when tone or formatting matters. Make the limits explicit, especially when the system might otherwise fill a gap with a plausible detail.
A brief you can reuse
Task: [What should be completed?] Audience: [Who will use or receive it?] Source material: [The notes, facts, or files to use] Useful result: [What a good answer must include] Limits: [What must stay out or require approval] Output: [The format and level of detail] Missing information: Flag gaps and ask before guessing. Review: Separate the draft from anything that sends, publishes, or changes a record.
For a meeting follow-up, you could ask for a short email that names the agreed next step, uses the recipient’s preferred name, and marks any uncertain date for review. That is a clearer assignment than asking for a “professional email.”
Keep the useful parts
After reviewing the result, change the brief where it was ambiguous. If the system missed a detail that was never supplied, add the missing source. If it ignored a supplied fact, make that requirement easier to find and check.
Save a brief once it works well for a repeated task. Keep examples beside it, and update the facts when the work changes. A reusable instruction is only as useful as the information it points to.
You can start with the next draft you already need to write. Fill in the brief, review the result, and keep the corrections that would help the next attempt.