How artificial intelligence can speed up the analysis of lengthy documents

Many professionals regularly work with contracts, annual reports, and technical studies that span hundreds of pages. AI-powered tools can reduce the time spent reading these documents, but only if used systematically and with answers verified.

How AI assistants work with long texts

AI assistants operate using language models—systems trained to identify patterns in text and generate responses. Each model has a context window, which is the amount of text it can process at once. For larger files, the tool splits the content into sections or selects only the parts it deems relevant.

This process requires caution. Researchers from Stanford University and the University of California, Berkeley, demonstrated in a 2024 study published in Transactions of the Association for Computational Linguistics that models tend to make less effective use of the central parts of lengthy texts. In practice, information on page 120 might be omitted from a summary.

Four practical applications

Summarize by layers

Instead of simply asking, “Summarize the PDF,” first request a map of the chapters and their themes. Then, ask for section-specific summaries, specifying the length and target audience, such as, “Summarize chapter 3 in ten lines for a financial director.”

Locate arguments

Ask the tool to identify the central thesis, the supporting arguments, and the data used in each argument, always indicating the corresponding page. The same logic applies to contracts when searching for clauses related to deadlines, penalties, and termination.

Compare documents

When sending two versions of a contract or two reports from consecutive years, you can request a table showing what has changed, what has been removed, and what has been added. This feature is useful for addendums, internal policies, and financial statements.

How to verify answers in the original sources

Language models can produce incorrect information that appears certain, a phenomenon known as hallucination. A 2024 study by RegLab and HAI at Stanford University evaluated AI-based legal research tools and found incorrect answers in over 17% of queries in some systems and over 34% in others.

To reduce this risk, it’s recommended to ask the tool for the exact passage and page number of each statement. Then, open the PDF and use the search function (Ctrl+F) to locate the passage. Pay extra attention to numbers, dates, names, and values.

It also helps to instruct the AI to respond, “I didn’t find it in the document,” when the information doesn’t exist. This reduces the likelihood of invented answers filling gaps.

Before sending files to any tool, it’s important to review the service’s privacy policy and the company’s rules, as documents containing personal or strategic data may be subject to the General Data Protection Law (LGPD)