Fixing the Dataverse MCP "Describe" Tool FileLoadException in Copilot Studio

The problem

If your Copilot Studio agent uses the Dataverse MCP server and calls the describe operation (for example, "describe the account table"), you may have hit an error similar to this:

Something went wrong. Plugin context correlation ID: a6739c5d-b8ef-4b8c-8a81-75d7b5432a28.
Exception - System.IO.FileLoadException: Could not load file or assembly
'System.ServiceModel.Primitives, Version=4.10.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
or one of its dependencies. The located assembly's manifest definition does not match the assembly reference.
(Exception from HRESULT: 0x80131040)

The stack trace points to Microsoft.CDS.PowerAIExtensions.Plugins.Service.DataverseCore.McpGetSkillOperation, which is the internal plugin behind the Dataverse MCP describe/skill operation. Other MCP operations against Dataverse may continue to work, but describe calls fail every time with this assembly load error.

Root cause

Microsoft confirmed this was a known, Microsoft-side issue. A recent update to the PowerAIExtensions solution shipped with a dependency packaging regression, causing a version mismatch on System.ServiceModel.Primitives inside the plugin sandbox. It wasn't caused by anything in the agent configuration, connector setup, or DLP policy on the customer side.

Microsoft deployed a hotfix and, as part of the fix, asked affected customers to install (or reinstall) the PowerAIExtensions component in their environment so the environment picks up the corrected package.

The fix

1. Go to the Power Platform admin center (admin.powerplatform.microsoft.com).
2. In the left navigation, select Manage, then Dynamics 365 apps.
3. In the Name filter, search for poweraiextensions.
4. You should see Microsoft Dynamics 365 - PowerAIExtensions listed for your environment.
5. Select Install and wait for the install to complete.
6. Allow some time for the environment to pick up the update.
7. Republish your Copilot Studio agent.
8. Test the describe operation again.

Microsoft's guidance also pointed to their general knowledge/unstructured data documentation for context on component installation steps: Copilot Studio knowledge base article. Note this link is a general reference from support and not a page specific to this MCP fix, so treat it as background reading rather than a direct how-to.

Verification

After reinstalling PowerAIExtensions and republishing, retest the same prompt that previously failed (for example, "describe the account table" or "show me the tables in Dataverse"). If the describe operation still fails after the install has had time to propagate, raise a support ticket and include:

• The plugin trace ID from the error ([CIT:...] value)
• The plugin context correlation ID
• The Copilot Studio agent URL

Takeaway

Assembly load errors like this one, referencing internal Microsoft plugin namespaces such as Microsoft.CDS.PowerAIExtensions, are a strong signal the issue sits on the platform side rather than in your agent or environment configuration. In this case, reinstalling the PowerAIExtensions solution from the Power Platform admin center was enough to pull in Microsoft's corrected package and resolve the describe operation failure.