Size matters - Large documents and Copilot for Microsoft 365

Microsoft has published an article named Keep it short and sweet: a guide on the length of documents that you provide to Copilot. It describes how Copilot for Microsoft 365 reaches its limits when it has to work with large documents or very long emails.

The reason for this is that Copilot works with data from the Microsoft Graph, which means that the search in M365 also has a role here. Documents, emails and all other content must first be indexed by the search before they are available for Copilot. At least for the search in SharePoint Online, the limits are documented: https://learn.microsoft.com/en-us/sharepoint/search-limits.

The exact limits that apply for processing by Copilot in Microsoft 365 are currently unclear. The article Keep it short and sweet: a guide on the length of documents that you provide to Copilot gives the following recommendations:

• Shorter than 20 pages
• Maximum of around 15,000 words

The example shows how it behaves when relevant information is after these limit recommendations. The relevant information to be used via Copilot are as followed. These are on page 49 of a Word document that contains a total of 27,208 words.

If you ask Copilot “What can you tell me about Snabales Total liabilities?” you get the following answer:

If you use Copilot in Word and ask the same question, the answer is: “This response isn't based on the document: I'm sorry, but the document does not provide any information about Snabales Total liabilities...”

One option you now have here is not to use Copilot for Microsoft 365 natively, but to create your own solution based on Azure AI-Search and Azure OpenAI. In Azure AI-Search, a vector search can be used that splits large documents into so-called chunks. This article describes the details: Chunking large documents for vector search solutions in Azure AI Search