Copilot’s Automatic Summary for Word Documents

Automatic Document Summary in a Bulleted List

Last week, I referenced the update for Word where Copilot for Microsoft 365 generates an automatic summary for documents. This is covered in message center notification MC871010 (Microsoft 365 roadmap item 399921). Automatic summaries are included in Copilot for Microsoft 365 and Microsoft Copilot Pro (the version that doesn’t ground prompts using Graph data).

As soon as I published the article where I referred to the feature, it turned up in Word. Figure 1 shows the automatic summary generated for a document (in this case, the source of an article).

The summary is the same output as the bulleted list Copilot will generate if you open the Copilot pane and ask Copilot to summarize this doc. Clicking the Ask a question button opens the Copilot pane with the summary prepopulated ready for the user to delve deeper into the summary.

The summary is only available after a document is saved and closed. The next time someone opens the document, the summary pane appears at the top of the document and Copilot generates the summary. The pane remains at the top of the document and doesn’t appear on every page. If Copilot thinks it necessary (for instance, if more text is added to a document), it displays a Check for new summary button to prompt the user to ask Copilot to regenerate the summary.

Apart from removing the Copilot license from an account (in which case the summaries don’t appear), there doesn’t seem to be a way to disable the feature. You can collapse the summary, but it’s still there and can be expanded at any time.

Summarizing Large Word Documents

When Microsoft launched Copilot support for Word, several restrictions existed. For instance, Word couldn’t ground user prompts against internet content. More importantly, summarization could only handle relatively small documents. The guidance was that Word could handle documents with up to 15,000 words but would struggle thereafter.

This sounds a lot, and it’s probably enough to handle a large percentage of the documents generated within office environments. However, summaries really come into their own when they extract information from large documents commonly found in contracts and plans. The restriction, resulting from the size of the prompt that could be sent to the LLM, proved to be a big issue.

Microsoft responded in in August 2024 with an announcement that Word could now summarize documents of up to 80,000 words. In their text, Microsoft says that the new limit is four times greater than the previous limit. The new limit is rolling out for desktop, mobile, and browser versions of Word. For Windows, the increased limit is available in Version 2310 (Build 16919.20000) or later.

Processing Even Larger Word Documents

Eighty thousand words sounds a lot. At an average of 650 words per page, that’s 123 pages filled with text. I wanted to see how Copilot summaries coped with larger documents.

According to this source, the maximum size of a text-only Word document is 32 MB. With other elements included, the theoretical size extends to 512 MB. I don’t have documents quite that big, but I do have the source document for the Office 365 for IT Pros eBook. At 1,242 pages and 679,800 characters, including many figures, tables, cross-references, and so on, the file size is 29.4 MB.

Copilot attempted to generate a summary for Office 365 for IT Pros but failed. This wasn’t surprising because the file is so much larger than the maximum supported.

The current size of the Automating Microsoft 365 with PowerShell eBook file is 1.72 MB and spans 113,600 words in 255 pages. That’s much closer to the documented limit, and Copilot was able to generate a summary (Figure 2).

Although the bulleted list contains information extracted from the file, it doesn’t reflect the true content of the document because Copilot was unable to send the entire file to the LLM for processing. The bulleted list comes from the first two of four chapters and completely ignores the chapters dealing with the Graph API and Microsoft Graph PowerShell SDK.

Summaries For Standard Documents

Microsoft hasn’t published any documentation that I can find for Copilot’s automatic document summary feature. When it appears, perhaps the documentation will describe how to disable the feature for those who don’t want it. If not, we’ll just have to cope with automatic summaries. At least they will work for regular Word documents of less than 80,000 words.

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