A five-page document becomes five neat bullets. It is easier to read, but the sentence that begins “except when” may have disappeared. That small omission can change what the document means.
Define what must survive shortening
Before requesting a summary, decide which details matter for your purpose. For a product specification, that might include supported models, operating conditions and exclusions. For a meeting note, it might be the difference between a suggestion and a decision.
Ask for those distinctions explicitly. “Summarise this and separately list exceptions, unresolved questions and conditions” gives you more to inspect than a request for the main points alone.
Compare a claim with its boundary
Suppose a fictional guide says that an accessory works with models A and B, except when a particular adapter is used. A summary saying “compatible with A and B” is incomplete even if every word in it appears in the guide.
Pick the claims you might act on and find their supporting passages. Read the surrounding sentences and footnotes too. The boundary is often nearby rather than inside the quoted sentence.
Keep the original in the workflow
NIST and NCSC describe limitations and risks of generative systems; polished output should not be treated as a guarantee of accuracy. Use the summary as a route into the document. When forwarding it, include the original and clearly mark any questions you have not resolved. Brevity is useful only if the important qualifications remain visible.