Ask with a purpose
AI assistants are quick at shortening long text. You can paste in a report, a policy, or a long email thread and get the main points in seconds. But a plain "summarize this" gives you a generic result. The AI doesn't know what you care about.
Tell it why you need the summary. Compare these two requests:
- "Summarize this report."
- "I'm a team lead. Summarize this report in five bullets, focusing on what changes for my team and any deadlines."
The second one tells the AI what to keep and what to skip. You can also ask for a format, like a short table of dates or a list of decisions.
What summaries miss
A summary is a choice about what to leave out. That is the point, but it has a cost. Summaries tend to keep the main idea and drop the details. The details are often things like exceptions ("unless the order is over $500"), conditions, and small print.
AI summaries can also get things wrong. The AI might mix up who did what, flip a number, or state something the document never said. This is the same kind of error you learned to watch for when checking AI output.
Check against the source
If a summary will guide a real decision, check the parts that matter. Ask the AI to quote the exact sentence behind each key point, or to tell you which section it came from. Then find that spot in the original and read it yourself. If you can't find it, treat the point as unproven.
Asking "Are you sure?" isn't a real check. The AI may just repeat itself with more confidence.
When the document is too long
Every AI tool has a context window, which is the limit on how much text it can look at at once. A very long document may not fit. Some tools will warn you, but some quietly use only part of it. Then the summary covers the first half and misses the rest.
If a document is very long, split it into parts. Summarize each section on its own, then ask for an overall summary of those pieces. It takes a little longer, and you'll know every part was read.
Try it
Pick a long email thread or article you already know well. Ask an AI assistant to summarize it for a specific reader, such as a busy coworker. Then compare the summary with the original. Note one detail it got right and one it left out or got wrong.