New Foundry Custom MCP Server dialog box not retaining "Audience" parameter

Hi Greg Peatfield

I see in the image, this looks like a UI persistence bug in the Azure AI Foundry interface for configuring Custom MCP servers.

Here’s what’s happening:

• The Audience field is present in the dialog and is required for Microsoft Entra authentication when using Agent Identity.
• After you enter the Audience and click Update, the value is not retained when you reopen the dialog. This suggests the UI is not persisting the parameter to the backend configuration.
• Because the Audience is missing in the stored configuration, the agent fails to authenticate against your MCP server (since the token validation requires the correct Audience claim).

For Entra-based auth, the Audience is critical because it tells the token issuer what resource the token is intended for. If it’s missing, the MCP server rejects the token.

Recommended Actions

1. Verify API Behavior Check if the Audience is actually being saved in the backend by calling the Foundry API or inspecting the configuration JSON. If it’s missing there too, it’s definitely a persistence bug.
2. Workaround
   1. If the UI doesn’t retain the Audience, try using the Foundry CLI or REST API to update the MCP server configuration directly.
   2. Include the audience parameter explicitly in the payload when creating or updating the MCP connection.
   3. Double-check Agent Identity Settings Ensure the MCP server expects the same Audience you configured. Sometimes mismatched resource IDs cause silent failures.

   References:

   • Azure AI Foundry documentation
   • Model Context Protocol in Azure AI
   • Deploy a self-hosted remote Azure MCP Server
   • Troubleshooting Access Issues to MCP Server

I Hope this helps. Do let me know if you have any further queries.

Thank you!