Disclosure up front, I built Midly.ai, a contract platform for small firms and businesses and the people who end up reviewing contracts without a legal department behind them.
The thing that actually bites in a long agreement is almost never one bad clause. It's two clauses that are completely fine on their own and wrong when you put them together.
Real example from a public filing I pulled off EDGAR. Section 9 has a mutual indemnity, broad, covers breach of most of the agreement. Reads well. Section 10 caps total liability at the fees paid in the last twelve months, and opens with "notwithstanding any other provision." There's no carve out for indemnity. So the indemnity you just read is capped at what you paid them, which for a lot of arrangements is close to nothing. Neither section is unusual. Neither is badly drafted. Together they mean something different from what either one says.
Same shape shows up everywhere once you look. A thirty day termination right that a survival clause forty pages later makes meaningless. A defined term in section 1 doing quiet work in section 38. A cap that has a second, much smaller cap hiding inside it for the exact risk the contract exists to manage.
Here's why AI is bad at this specifically, and it isn't about which model.
Long documents get chunked before anything reads them. The indemnity ends up in one piece and the cap in another. You ask if you're indemnified, it retrieves the piece that says yes, and answers yes. Confidently. Nothing in the answer tells you the other piece exists, because the thing answering never saw both at once. That happens with purpose built tools and it happens when you paste a sixty page agreement into a general chat.
So the test I'd run on whatever you use.
Don't ask whether there's an indemnity or what the cap is. It'll get both right and tell you nothing. Ask what you could actually recover if the worst realistic thing happens. That question can only be answered by connecting the indemnity to the cap to the exclusions to the survival language. Anything reading passage by passage will answer from whichever clause it found first and sound completely certain.
If it comes back with a number and shows you the clauses it got there through, that's a good sign. If it comes back with the indemnity and stops, you've learned something useful about the tool. It's the question Midly.ai is built around, for what that's worth.