A 40-page contract lands in your inbox, and every summarizer you’ve tried nails the opening, nails the closing, and quietly skips whatever sits in the middle. Reddit user netra_2428 posted a fix for that in r/ChatGPTPromptGenius: a prompt built to force even coverage across the whole document and to catch its own hallucinated numbers before you act on them. Short version: it separates “what the document says” from “what the AI made up,” and that second part is worth stealing even if you skip everything else.
🔍 How It Actually Works
The prompt opens by making the model classify the document before it summarizes anything. One line stating what type of document this is and what it’s mainly for. That single line forces the model to load the right context instead of guessing tone halfway through the summary.
That’s really the core idea behind why this prompt runs longer than a typical one-liner. A vague instruction like “summarize this” lets the model decide what matters, and it usually decides based on what compresses easiest, meaning the intro and the conclusion. Spelling out order, weighting, and a mandatory self-check removes that guesswork.
From there it locks in a fixed order: TL;DR in two sentences, then key points weighted by importance and explicitly told to cover the middle of the document, not just the edges. Most long-document summaries front-load the intro and coast on the conclusion. This prompt is told directly not to do that.
Next comes a section for decisions, obligations, and action items, tagged with who’s responsible and any dates mentioned. If the document doesn’t spell that out, the model is told to write “none stated” instead of inventing a deadline that sounds plausible.
Then it pulls every number that matters (amounts, deadlines, percentages) into its own short list, followed by the one thing a busy reader would most likely miss. That last line is the part that turns a summary into something you can actually act on!
The Self-Check Is the Real Feature
The last rule in the prompt is the one netra_2428 says they’d keep even if they stripped everything else: after the summary, the model has to list any name, date, or number in its own output that doesn’t appear in the source document.
That’s a built-in lie detector. AI summaries love to invent a confident-sounding deadline or a round number that was never in the text. Making the model audit its own output catches those hallucinations before you forward the summary to your boss or your legal team.
There’s also a practical trick for documents too long to paste in one shot. Feed the PDF in sections, run the prompt on each one, then paste all the section summaries back in and run it once more over those. That two-pass approach is what stops the middle from getting dropped in the first place.
📌 Use Cases
- Contracts: catch obligations and dates buried in clause 14 that a plain summary would skip.
- Research PDFs: keep findings from page 20 as visible as the abstract on page 1.
- Board reports and long memos: pull the one overlooked detail before a meeting, not during it.
- Anything with numbers you’ll quote later: the self-check flags fake figures before they end up in your own writeup.
Prompt of the Day
Paste this ahead of any long PDF, contract, or report:
You are summarizing a long document for someone who has to act on it, not just get the gist.
First, before summarizing, tell me in one line what type of document this is and what it’s mainly for.
Then produce, in this exact order:
- TL;DR in 2 sentences.
- Key points as bullets, most important first. Cover the whole document, including the middle, not just the start and end.
- Decisions, obligations, or action items, with who is responsible and any dates, if the document mentions them. If none, say “none stated.”
- Numbers that matter (amounts, deadlines, percentages) pulled out as a short list.
- The one thing a busy person skimming this would most likely miss.
Rules:
- Do not invent anything. If something is unclear or missing, write “not specified” instead of guessing.
- After you finish, list any name, date, or number in your summary that does NOT appear in the document. This is a self-check for made-up details.
DOCUMENT: {{paste the text}}
One tweak worth trying: swap the closing self-check for a stricter version that also flags any claim the model couldn’t tie back to a specific line in the source. That turns the prompt from “catch hallucinated numbers” into “catch hallucinated claims,” useful for legal or medical text where a clause reference matters as much as a dollar figure.
If you run this on your own PDFs, or tweak it into something sharper, netra_2428’s original thread is worth a look. Other readers there are already comparing notes on which document types manage to trip it up.
A copy-paste prompt for summarizing a long PDF without losing the parts that actually matter
by u/netra_2428 in ChatGPTPromptGenius