Summarise a long document without losing the point
Stop asking it to "summarise this" and ask three or four specific questions about what you actually need to know, demanding for each answer the literal sentence from the document that supports it. A generic summary is correct and answers none of your questions; a list of questions tells you exactly what affects you and where it comes from.
Why "summarise this" fails
Because the AI has no idea what matters to you. A twenty-page contract has a different summary for the person signing it, the person who has to deliver it and the person comparing it with another. Not saying which one you are gets you the average summary: the one that serves none of the three.
The questions that do work
- "What obligations does this put on me, with the exact sentence for each?"
- "What deadlines and dates appear, and what happens if they are missed?"
- "What can be cancelled, how, and with how much notice?"
- "What is unusual here compared with a normal document of this kind?"
- "What does this document NOT say that it should?"
The last two pay off most and almost nobody asks them.
Signs you cannot trust it
- There is no supporting sentence, or the sentence quoted is not in the document.
- The summary is as detailed at the end as at the start: usually it only read the start properly.
- Round figures appear that are nowhere in the text.
- It answers confidently about something the document could not possibly contain.
A quick trick for the last one: ask about something you know is not there. If it invents an answer, you now know how to treat the rest.
The honest limit
A summary tells you where to look; it does not replace reading what you are about to sign. It is for deciding which pages you genuinely have to read, and that is already most of the saving.
The summary is not the goal: knowing what affects you and where it is written down is.