AI Guides › Prompting
The Difference Between "Summarise This" And "Tell Me What I'm Missing"
By Nigel Guy · 2 min read
"Summarise this" is the default request for any long document, and it's the
right one far less often than people reach for it. A summary compresses what
is already there — it's a shorter version of the same information, weighted
toward whatever seems most central. It cannot tell you about a gap, a missing
clause, or a claim the document quietly avoids making, because none of that
appears in the text to be compressed. If what you actually need is "is there
a problem in here," a summary is the wrong tool wearing the right disguise.
The rule: summarising compresses what's there; a gap-check looks for what
isn't — decide which one you actually need before you ask for either.
The mechanism
Use this quick sort before reading a long document:
- Ask yourself what you'll do with the answer. If you're about to make a
decision, sign something, or rely on the document being complete, you need
the gap-check. If you just need to know the general shape of it before a
meeting, a summary is fine.
- For a gap-check, ask directly for absence, not content. "What would a
careful reader expect this document to cover that it doesn't?" or "what
claims does this make without evidence?" — questions shaped around what's
missing, not what's there.
- Name the category of gap you care about. "Missing" is broad — narrow
it to what matters for your case: missing numbers, missing dates, missing
counterarguments, missing edge cases. A named category gets checked more
thoroughly than an open-ended one.
- Run both, separately, on anything that matters. A summary orients you;
a gap-check protects you. They answer different questions and doing one
doesn't cover the other.
What to skip
Skip the gap-check on anything you're just skimming for general awareness —
it's slower and it's built for documents you're about to act on. And skip
treating a clean gap-check as proof the document is sound; it only means the
categories you asked about weren't obviously missing.
Guardrails
- A gap-check can only flag what it's pointed at. It won't surface a category
of problem you didn't think to ask about.
- Neither a summary nor a gap-check replaces reading the actual document
yourself when the decision genuinely matters — treat both as a first pass.
- For anything with legal, financial, or contractual weight, a flagged gap
(or a clean pass) is a prompt to get a qualified person to look, not a
verdict on its own.
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