.NET: Foundry Agent - MCP fails server side. No error propagated to client #1643
Description
Hi,
On Agent Framework version: 1.0.0-preview.251016.1
I referenced an MCP server in a Foundry Agent. The Foundry Agent fails when I run the thread.
I can see the following message in Fiddler:
event: thread.run.failed
data: {
"id": "run_AptSDFasdasddasd",
"object": "thread.run",
"created_at": 1761180339,
"assistant_id": "asst_asdasdasd",
"thread_id": "thread_asdasdas",
"status": "failed",
"started_at": 1761180340,
"expires_at": null,
"cancelled_at": null,
"failed_at": 1761180340,
"completed_at": null,
"required_action": null,
"last_error": {
"code": "tool_server_error",
"message": "Error: list_tools_server_error; Server error while listing tools: Failed to enumerate tools from remote server: https://8e5c3d750dc4.ngrok-free.app:443/. Response status code does not indicate success: 405 (Method Not Allowed)."
},
"tools": [
{
"type": "mcp",
"server_label": "WeatherMcp",
"server_url": "https://sdfasdasdadasdaddas.ngrok-free.app",
"allowed_tools": null
}
],
...
}
A call to await agent.RunAsync completes successfully, with an empty string in the Agent Message.
Would expect an exception, or something to indicate the failure in the RunAsync response.
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[-]Foundry Agent - MCP fails server side. No error propagated to client[/-][+].NET: Foundry Agent - MCP fails server side. No error propagated to client[/+]tonybaloney commentedon Oct 23, 2025
Python has the same issue. All of my MCP calls timed out (the endpoint was broken) but instead of erroring the workflow, it continued and hallucinated the output.
rogerbarreto commentedon Dec 1, 2025
The root cause of this issue is related to the
which was recently addressed, I'm closing this issue as resolved and the fix should be available as soon a new release of
Azure.AI.Agents.Persistentpackage is included in MAF next release.