Copilot Studio Preview : MCP Agent works in Teams but not in Microsoft 365 Copilot Chat

I’m currently testing the new preview version of Copilot Studio and I ran into a behavior I’d like to validate with the community.

I created a custom Copilot agent using the new interface, connected to a Microsoft Learn MCP server (for retrieving official documentation), and deployed it across both:

- Microsoft Teams

- Microsoft 365 Copilot (Copilot Chat)

Configuration-wise, everything seems correctly set up:

- Agent published

- Channel enabled for Teams and Microsoft 365 Copilot

- Permissions and access configured

- MCP tool working properly

Here is the key point:

- In Microsoft Teams:

The agent works perfectly.

It correctly calls the MCP server, retrieves Microsoft Learn documentation, and returns accurate responses.

- In Microsoft 365 Copilot Chat:

The same agent does not work at all.

No MCP call is triggered, and no response is generated from the agent.

Instead, Copilot returns the following message:

"Sorry, I am not able to find a related topic. Can you rephrase and try again?"

Even with:

- Explicit invocation using @AgentName

- Very simple prompts

- Minimal instructions

- Added knowledge sources (for testing)

The behavior remains the same.

At this point, it looks like:

- The agent is accessible and deployed

- But it is not actually executed by the Microsoft 365 Copilot runtime

Has anyone experienced the same behavior with agents in the new Copilot Studio preview, especially when using MCP tools?

Is there any known limitation or requirement for agents to be properly executed inside Microsoft 365 Copilot Chat (compared to Teams)?

Thanks in advance for your feedback.