The citation is the feature
Every "chat with PDF" tool will answer your question. The one thing that determines whether the answer is worth anything is whether you can check it in five seconds. Thaxas puts a numbered citation on each claim, pointing at the page in your document; clicking it takes you there. If the citation doesn't support the sentence, you have caught the error immediately — and that is the difference between a study tool and a very persuasive liar.
Three independent layers keep answers honest
- A similarity floor. Before the model is called at all, retrieval checks whether anything in your document is actually relevant. If nothing clears the threshold, generation never happens — the model is not given the chance to improvise.
- A refusal instruction. The system prompt requires an explicit sentinel when the retrieved passages don't answer the question, rather than allowing a graceful-sounding hedge.
- A visible badge. Answers that ran outside your material are marked as such in the interface. You are never left to guess which mode you're in.
Any one of these can be defeated. All three at once is a much harder thing to slip past, and the combination is why we're comfortable putting the tool in front of someone the night before an exam. The longer argument is in why AI study tools hallucinate.
It isn't only PDFs
The same grounded chat runs over anything you can get into a space: PowerPoint and Word files, plain text and Markdown, photos of handwritten notes, web pages, and audio lectures — which are transcribed, so a citation can point at a timestamp in a recording as easily as a page in a book. Put an entire module in one space and the chat can answer across all of it at once.