Azure AI Foundry Agent cannot call an MCP server

Yeah so got it working by adding this to the middleware

if (context.Request.Method == HttpMethods.Delete)

{

    Console.WriteLine($"Intercepted MCP DELETE session call at {context.Request.Path}");

    var sessionId = context.Request.Headers["Mcp-Session-Id"].ToString();

    Console.WriteLine($"Session ID: {sessionId}");

    context.Response.StatusCode = StatusCodes.Status200OK;

    context.Response.ContentType = "application/json";

    await context.Response.WriteAsync("{\"result\":\"session ignored\"}");

    return; // Don't call next middleware — stops further processing

}  

So I guess my question is why is the Foundry agent calling DELETE before it has called the tool? And how do I stop it doing that?

Hey Joe Bacon I am in same problem but my mcp server is python sdk. Was wondering since its a sample do you have it in a repo that is shareable or share the server code here? I am encountering same issue and will figure out with Ravada Shivaprasad comment but I didnt follow as well on what they meant

Hi Julio Aguilar

The agent may issue a DELETE request to clean up stale or expired sessions before initiating a new one. This is especially true if the previous session was incomplete or had errors

Ravada's suggestion was to handle session handling of MCP server side properly

Here are few areas to check the issue

• Check Session Handling Logic Review how the server handles DELETE / requests. Ensure it only deletes sessions that are truly expired or invalid.
• Improve Error Propagation Modify the MCP server to preserve and return detailed error messages when tool execution fails. This will help diagnose why tools/call is not triggered.
• Validate Request Format Ensure the agent sends a properly structured MCP request: JSON { "method": "tools/call", "params": { "name": "echo", "arguments": { "message": "test" }, "_meta": { "progressToken": 4 } } }
• Enable Verbose Logging Add detailed logging to the MCP server to trace session creation, deletion, and tool invocation attempts.

Hope it helps

Thank you

Hi @Julio Aguilar sure, it's in a private repo at the moment but I'll create a public one and copy it over and share the link.

Hi @Manas Mohanty thanks for the info. Do you have any documentation or code examples of how to manage sessions? None of the documentation I have read suggests that we need to manage sessions in code, or indeed the best practices on how to do that. Also, that delete method is called every time, regardless if the previous sessions were erroring. It would be great to get an idea as to why it is doing this, as catching all delete requests and having to manage the sessions/Mcp-Session-Id at the MCP server end seems a bit hacky, but please let me know if I'm just misunderstanding something. Cheers!

OK I have been reading up on session management here: https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#streamable-http

So it seems like the client (the Agent in this case I'd assume?) thinks that it no longer need a particular session, before it has called tools/call - and therefore sends a DELETE.

Do you have any documentation on how is best to set up session management if it is not handled for us in app using the base:

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddMcpServer()
    .WithHttpTransport()
    .WithToolsFromAssembly();

var app = builder.Build();
app.MapMcp();

Hi Joe Bacon

Good day. Sorry for the delay in responding.

Are you using Python/Rest API documentation already for MCP server calls

https://learn.microsoft.com/en-us/azure/ai-foundry/agents/how-to/tools/model-context-protocol-samples?pivots=python

I am trying to reach product group internally on this to save replication effort and time

Please share the details requested in private message on this thread to facilitate

.

Thank you

Hi Joe Bacon

I have gone through below articles to under creation of MCP server with dotnet.

https://learn.microsoft.com/en-us/dotnet/ai/quickstarts/build-mcp-server

(official repo from Azure)

https://medium.com/@mutluozkurt/creating-an-mcp-server-and-client-with-net-a-step-by-step-guide-0c3833dde3c4

(external reference)

But not Sure on advising optimization on below code. We don't help customer on setting up custom MCP server. It should be addressed web and Mobile team

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddMcpServer()
    .WithHttpTransport()
    .WithToolsFromAssembly();
var app = builder.Build();
app.MapMcp();

Thank you for understanding.

Hi Joe Bacon

Found an external reference on MCP server session management (not much in Azure Side)

We can Max Idle session time and Idle time out along max session.

builder.Services.AddMcpServer()
    .WithHttpTransport(options =>
    {
        options.IdleTimeout = TimeSpan.FromMinutes(30);
        options.MaxIdleSessionCount = 100;
    })
    .WithToolsFromAssembly();

Would it be possible to get reference document for setting up the MCP server to forward to PG.

Thank you.