Can a Copilot Studio custom agent be accessed from Copilot for Excel?

Question

Subject: Can a Copilot Studio custom agent be accessed from Copilot for Excel?

Hi everyone,

I'm evaluating a solution using Microsoft Copilot Studio and would like to understand whether the following scenario is currently supported or planned.

Use case

Our users work with Excel workbooks stored in SharePoint (primarily .xlsb files).

• Users open a workbook in Excel and use the built-in Copilot for Excel for standard workbook questions (formulas, analysis, summaries, etc.).
• We want to build a custom agent in Copilot Studio that handles a specialized use case, for example, comparing two versions of the same Excel workbook stored in SharePoint and summarizing the differences, etc.
• Ideally, users would access this custom capability from within the Copilot for Excel experience rather than switching to Microsoft 365 Copilot Chat.

Questions

1. Is it currently possible to access a Copilot Studio custom agent directly from the Copilot for Excel interface?
2. If yes, what is the recommended and supported architecture?
3. Can the built-in Excel Copilot continue handling standard workbook questions while only specific requests (such as "compare workbook versions") are routed to the custom agent?

If automatic routing isn't supported, is there a supported way for users to invoke the custom agent from within Excel (for example, via agent picker, skills, or @mentions)?

Does this scenario work with .xlsb workbooks stored in SharePoint?

What I've found so far

I already came across the following Microsoft Q&A thread:

https://learn.microsoft.com/en-ie/answers/questions/5525545/how-do-i-select-an-ai-agent-in-copilot-within-exce

The accepted answer mentions that the Excel agent-picker experience was preview-only and available only in certain Insider builds/flighted tenants. However, since Microsoft Q&A responses are community/support guidance rather than official product specifications, and the thread dates back to August 2025, I'm not sure whether this is still the current state or whether anything has changed since then.

Roadmap

Finally, does anyone know whether Microsoft has a public roadmap for this capability?

Specifically, I'm interested in whether Microsoft plans to support:

• Accessing Copilot Studio custom agents directly from Copilot for Excel,
• Intent-based routing between the built-in Excel Copilot and custom agents, or a general availability timeline for this functionality.

Any guidance from the product team or anyone who has implemented this successfully would be greatly appreciated.

Thanks!

Answer 1

Thanks for the detailed scenario. Based on the current Microsoft 365/Copilot Studio capabilities:

1. Can a Copilot Studio agent be accessed directly from Copilot for Excel?

Yes, a Copilot Studio agent can be published to the Microsoft 365 Copilot channel and made available to users. However, this should not be interpreted as the agent being natively embedded as an Excel Copilot skill.

2. What is the recommended architecture?

The recommended pattern is:

Excel → Microsoft 365 Copilot → select/@mention the Copilot Studio agent → agent performs the specialised task

The custom agent can then use actions/Power Automate/connectors to retrieve and compare the required SharePoint files.

3. Can Excel Copilot handle normal questions while the custom agent handles specific requests?

Yes, but I would not rely on automatic routing. Excel Copilot can continue handling normal Excel questions, while users explicitly invoke the specialised agent when they need functionality such as workbook comparison.

4. Can the custom agent be invoked from within Excel?

The supported approach is to make the agent available in Microsoft 365 Copilot and have users explicitly select or @mention it where that experience supports agent invocation. I would not describe automatic skill-based routing from Excel Copilot to a Copilot Studio agent as currently supported.

5. Does this work with .xlsb files in SharePoint?

.xlsb files are supported by Excel/SharePoint scenarios, but for your specific requirement—comparing two workbook versions—I would recommend a dedicated action/flow/backend process rather than relying on the files being treated as Copilot Studio knowledge.

In short: Yes to publishing the agent to Microsoft 365 Copilot; no clear support for automatic routing from Excel Copilot; and for .xlsb comparison, use a deterministic processing flow/action.