How to ask questions about your documents and get answers you can check

"What notice period does the Harbour Street lease require?" is a question with one right answer, sitting on one page of one PDF. Asking an AI tool should be faster than finding the PDF, opening it and scrolling. Often it is. Sometimes it confidently quotes the notice period from a different lease.

Both outcomes come from the same machinery. Once you know how it works, you can word questions so it finds the right passage, and spot quickly when it has not.

Download PlexiiDesk free if you want to try this on your own files as you read. Personal use costs nothing, on Mac or Windows.

How document Q&A actually works

Almost every tool that answers questions about your documents works in two steps.

Step one: find. The tool searches your documents for passages that look relevant to the question. It does not read everything you own every time you ask; it picks a handful of passages.

Step two: answer. The AI model reads only those passages and writes an answer from them.

That split explains nearly every failure:

• If step one misses the passage, step two cannot use it. The answer will be incomplete, or the model will fill the gap from general knowledge.
• If step one finds the wrong passage, step two will faithfully summarise the wrong thing. That is how you get the notice period from the other lease.
• If the passage is ambiguous, the answer will be too. A model cannot resolve a contradiction that is in your documents.

So the quality of the answer depends heavily on whether the search found the right material. Good tools show you what they found, so you can judge that yourself.

Words versus meaning

Searches find passages in one of two ways, and many tools use both.

By words. The search looks for passages that share words with your question. Fast and predictable, but literal: ask about "staff turnover" and it may miss a report that only says "attrition".

By meaning. The search compares what the question means with what each passage means, so "turnover" can find "attrition". This needs an extra model to work out meanings, which some tools run in the cloud and some on your computer.

If a tool tells you which one it used, you can adjust. Searching by words means using the vocabulary of the document, not your own.

How to word a question

These habits help with any tool.

Name the document when you know it. "In the Harbour Street lease, what is the notice period?" beats "what's the notice period?". If the tool lets you point at a document directly, do that: it removes step one entirely.

Use the document's words. If the contract says "termination", ask about termination, not "getting out of it".

Ask one thing at a time. "What is the notice period, and has the rent review clause changed since 2024?" asks the search to find two different passages at once. Ask twice.

Ask for the quote. "Quote the clause that sets the notice period" makes the answer easy to check and makes paraphrase errors obvious.

Say what to do when it is not there. "If the documents do not say, tell me" gives the model permission not to guess.

Where different tools look

How much ground a tool covers matters as much as how well it reads.

Tools that answer from files you upload. You give it a defined set of documents and ask questions about them. Google's NotebookLM (opens in a new tab) works this way: answers come from the sources you add to a notebook, with citations, and free accounts can add up to 50 sources per notebook. This suits a fixed set, such as the papers for one literature review or the documents for one tender.

Tools that answer from where your work already lives. The search runs across your documents, notes, spreadsheets, files and sometimes email, without you choosing the set first. This suits questions where you do not know which document has the answer, which is most questions at work.

The trade-off is focus. A defined set rarely returns a passage from the wrong project. A whole-workspace search finds more, and needs ways to point it at the right place.

Asking your documents in PlexiiDesk

In PlexiiDesk, the Plexii assistant answers from your workspace. It sees the desk you are on and searches your documents, desks, tables, notes, PlexiiBrain, files, meetings, past chats and connected mail. What it reads, in detail:

• Files with readable text, including PDFs (scanned ones too), Word documents, spreadsheets and CSV files, up to 15 MB each
• Tables: each table's title, column names and its first 40 rows
• Calendar entries from six weeks back to six weeks ahead
• Mail, if connected: only the messages that match your question, not your whole mailbox

The full list is in What Plexii can read and search.

Asking from a desk does not limit the search to that desk, but the desk's own material comes first. So ask about the Harbour Street lease from the Harbour Street desk.

Point at it with @. When you know which document you mean, type @ and pick it. Plexii reads what you mention in full, before it searches. It is the surest way to work from the document you have open. See Point Plexii at specific things with @.

Check the trace. Above each answer, the trace lists every source the search returned, numbered, with where each lives. In the answer, a number such as [2] follows each statement that rests on a source; click it to open the source in a window over your work. Chips under the answer show only the sources the answer actually cited. If the trace's workspace line ends in keyword match, the search was by words only. Adding an OpenAI key, or running AI on your computer with Local on this device, lets it match by meaning too. See See what Plexii read and check its sources.

Ask from inside a file. In PlexiiCells, PlexiiDeck and the design app, Ask your workspace sits at the top of the assistant panel, so you can pull a figure from a report into a spreadsheet without leaving it. See Ask your workspace from a spreadsheet, deck or design.

To ask questions about your own documents with citations you can open, download Plexii free.

Answers need AI: PlexiiDesk credits while you are signed in, or your own key. Plexii is free to download and free forever for personal use (pricing). The Plexii assistant section of the product tour shows the set-up in one place.

A two-minute check before you rely on an answer

When the answer matters, a contract term, a figure in a report, a date you will act on, check it:

1. Open the cited source for the claim you will act on. Not all of them; the one that matters.
2. Find the passage. Does it say what the answer says, in context? Watch for "except", "unless" and "subject to".
3. Check it is the right document. Right lease, right version, right year.
4. Look at what was found but not cited. A source the answer ignored may be the one that disagrees.
5. If nothing was cited, treat it as a guess. Ask again, pointing at the document.

How to check an AI answer before you rely on it goes further, including what to do with numbers and names. The design rules behind our assistant are in show your sources, ask before you act, and AI at work covers practical uses and what changes for the people doing the work. For a longer view of searching your own notes, see a second brain for work that keeps its sources. More guides are in the AI you can check hub.

Common questions

Can AI answer questions about my PDFs? Yes, if the PDF has text the tool can read. Some tools also read scanned PDFs by recognising the text in the images. Check that the answer cites the PDF and the page or passage you expect.

Why did the AI miss something that is in my document? Usually because the search step did not find the passage, often because your question used different words from the document. Name the document, use its wording, or point the tool at it directly.

Is it safe to ask AI about confidential documents? It depends on where the AI runs and your organisation's rules. Find out whether your documents are sent to a cloud model, under whose account, and whether you can choose a model that runs on your computer.

What is the difference between searching and asking? Searching returns a list of matching documents for you to read. Asking returns a written answer built from the passages a search found. Searching first and asking second is a good way to check an answer.

How do I make AI quote the source? Ask for it directly: "quote the clause" or "give me the exact sentence". A quote is easier to check than a paraphrase.

Can I ask questions across many documents at once? Yes. Ask the question without naming a document and the tool searches across them. For comparisons, ask about one document at a time, then compare the answers.