Understand a contract with AI: what it can and can't tell you

A plain-language first read of a contract, not a legal opinion. Open Explain PDF, add your contract as a text PDF, and you get a structured reading in everyday words. The tool says on the page that it isn't legal or medical advice, and that's the right way to treat it.

The read covers four things:

• What the document is. The type, the parties, the purpose and the period it covers.
• What it asks of you. Payments, duties, deadlines you must meet, things you must not do.
• Numbers and dates. Amounts, fees, start and end dates, notice periods.
• What to check. Parts that deserve a second look or a question to the other side.

It runs on Claude Haiku 4.5 at 5 Gems per run, and you see the cost before you run it.

A clear line before the details: this is a first read. It helps you know what you've been handed and what to ask. It can't tell you whether a clause is enforceable, fair or even legal where you live, and it doesn't replace a lawyer.

After the first read, use the chat to dig in (how to chat with a PDF covers the routine). For a lease or a service contract, seven topics catch most of the surprises:

• Notice period. How much warning must you give to leave, in what form, and from which date does it count?
• Auto-renewal. Does the contract roll over by itself, for how long, and by when must you cancel to stop it?
• Penalties. What happens if you pay late, leave early or break a rule? Are the amounts fixed?
• Who pays for repairs. Which costs fall on you, which on the other party, and what counts as normal wear?
• Deposit. How much, where it's held, when it comes back, and what can be deducted?
• Liability. What are you responsible for if something is damaged or goes wrong? Is the other side's responsibility limited?
• Changes to terms. Can the other party change prices or rules, with how much notice, and can you leave if they do?

Ask one topic per message, and ask for the clause number or the quoted sentence each time. Contracts bury the exception in a sub-clause, and a paraphrase hides it.

Say you have a fictional 12-page apartment lease. It's an example, not a real file and not a model's output. After the Explain read you have the outline: a landlord, a monthly rent, a 12-month term.

Now you read it again, hunting for four clauses that could cost you money, and turn each into a question. They're below. Notice that each one asks for the quote, and that the last one asks the model to say when the lease is silent. If the lease doesn't cover something, you want to hear that, not a guess at what's "normal".

Plenty, and most of it sits outside the text the model was given.

• Annexes in separate files. Price lists, house rules and inventory sheets often come as their own files. If you didn't upload them, nobody read them, and the contract may say they form part of the deal. Chat takes one file, so put them together with Merge PDF first.
• Side agreements. A promise made by email or by handshake isn't in the PDF. Neither is an amendment signed later.
• Scanned pages. A page with no text layer is invisible, and there's no OCR here. If part of the contract was scanned and pasted in, check in your viewer that every page you care about has selectable text.
• Local law. The same clause can mean different things, or be void, depending on the country or state. A model reading the text doesn't know your local rules on deposits, notice or rent increases.
• What is NOT written. The biggest gap. If a lease says nothing about who pays for a broken boiler, the answer comes from law and custom, not from the document. Ask "what does this contract not say about X?" and treat the answer as a question for someone who knows local rules.

And the model can simply be wrong. Open the page it cites and read the sentence yourself.

Soon, if any of these is true:

• A lot of money is involved: a long lease, a business contract, a loan, a purchase.
• The contract limits your rights in a way you don't follow, or asks you to waive something.
• You're being pushed to sign fast, or the other side won't answer questions.
• A dispute has started or a deadline is close.
• The answer depends on local law, which a read of the text can't settle.

Use the first read to make that meeting more focused. Bring the clause numbers, your questions and a list of what's missing (the annexes, the emails). A lawyer can answer "is this clause enforceable here?" A model reading a PDF can't. For a small, routine agreement a first read may be all you need, but the decision to sign stays with you.

When the other side sends a revised contract, Compare PDFs reads both and reports what differs. It needs exactly two files and a paid plan (the free plan's input cap is too small for two PDFs), and it runs on Claude Sonnet 4.6 at 5 Gems per run.

It's a text comparison by a model. It isn't a visual diff and it isn't a tracked-changes view, so you won't see struck-out words in colour. Ask for specific kinds of change: "List every change in amounts, dates, notice periods and penalties between version 1 and version 2. For each, quote both versions and name the clause."

Two habits help. Say which file is which in your question. And don't trust a closing line like "no other changes": a model can miss a reworded sentence. If the contract matters, read the flagged clauses side by side, then ask a second question about a topic you worry about, such as liability.

The AI jobs upload the PDF to the model provider you picked, and in chat the file is sent again with each message. A contract can contain names, addresses, ID numbers and bank details. The tool can't edit or black out text inside a PDF, so decide before you upload whether that's acceptable. If it isn't, don't use it on that file.

If you only need part of a long contract, choose a page range. The tool cuts it out on your device first, so only those pages leave it. How to summarize a long PDF walks through that.