A summary for a decision looks nothing like a summary for a record. Say which one you need.
Summarise for a decision, not for completeness
'Summarise this document' optimises for coverage, so you get a shorter version of everything. Say who is reading and what they must decide, such as 'a CFO deciding whether to approve next quarter's hiring budget', and the model can drop nine tenths of the document as irrelevant, which is the actual job.
Say what to ignore
Naming the sections that do not matter is faster than listing the ones that do, and it is more reliable. 'Cover revenue, burn and headcount, ignore marketing commentary' gives the model permission to leave things out, which it will not otherwise take.
Guard against the confident inference
Add: 'where the report lacks data for a claim, say it is missing rather than inferring it'. Summarisation is where models quietly fill gaps, and a fabricated number in a three-bullet summary is far more dangerous than one buried in prose, because nobody goes back to check three bullets.
Try it
Say who reads it, what they must decide, and what to leave out. Aim for a score of 85+.
48structure
Target: 85. Keep working the prompt. The score moves as you type.
⌃Role / persona: Open with a persona, e.g. "You are a senior backend engineer."
⌃Context: Front-load all context the model needs: inputs, audience, goal, and constraints, so it can answer in one shot.
⌃Constraints: State limits and do/don't rules, e.g. "Keep it under 200 words. Do not invent APIs."
Want it as a form instead? The document summary template has all seven parts already in place. Replace the brackets and paste it. For practice against a fresh brief, there is a new drill every day.