Bug: ModelContextProtocol.McpException: Transport is not connected

[hemantkathuria]

Add Mcp Tools and keep on getting the below error randomly

fail: Microsoft.SemanticKernel.KernelFunction[0]
Function Tools-GetCropHealthParameters failed. Error: Transport is not connected
ModelContextProtocol.McpException: Transport is not connected
at ModelContextProtocol.Shared.McpSession.SendRequestAsync(JsonRpcRequest request, CancellationToken cancellationToken)
at ModelContextProtocol.McpEndpointExtensions.SendRequestAsync[TParameters,TResult](IMcpEndpoint endpoint, String method, TParameters parameters, JsonTypeInfo1 parametersTypeInfo, JsonTypeInfo1 resultTypeInfo, Nullable1 requestId, CancellationToken cancellationToken) at ModelContextProtocol.Client.McpClientTool.InvokeCoreAsync(AIFunctionArguments arguments, CancellationToken cancellationToken) at Microsoft.SemanticKernel.ChatCompletion.AIFunctionKernelFunction.InvokeCoreAsync(Kernel kernel, KernelArguments arguments, CancellationToken cancellationToken) at Microsoft.SemanticKernel.KernelFunction.<>c__DisplayClass31_0.<<InvokeAsync>b__0>d.MoveNext() --- End of stack trace from previous location --- at Microsoft.SemanticKernel.Kernel.InvokeFilterOrFunctionAsync(NonNullCollection1 functionFilters, Func2 functionCallback, FunctionInvocationContext context, Int32 index) at Microsoft.SemanticKernel.Kernel.OnFunctionInvocationAsync(KernelFunction function, KernelArguments arguments, FunctionResult functionResult, Boolean isStreaming, Func2 functionCallback, CancellationToken cancellationToken)
at Microsoft.SemanticKernel.KernelFunction.InvokeAsync(Kernel kernel, KernelArguments arguments, CancellationToken cancellationToken)

[SergeyMenshykh]

Hi @hemantkathuria, it's quite difficult to tell what is going on without having the code. Please create a console app that reproduces this behavior and share it with us so we can start investigating. The first thing to look at would be the disposed McpClient that your app cached/keeps a reference to for accessing the McpServer.

[SergeyMenshykh]

Link to the same issue in MCP C# repo - modelcontextprotocol/csharp-sdk#333

[hemantkathuria]

Hello @SergeyMenshykh
It is a web app where I am facing this.
Below is the code in startup. But let me also try upgrading the package as suggested in MCP repo

`// Add Kernel
IKernelBuilder kernelBuilder = builder.Services.AddKernel();

string mcpServerUrl = builder.Configuration.GetSection("MCPClient").GetValue("MCPSSEServerUrl");

await AddTools(mcpServerUrl, kernelBuilder);

//Add Azure Open AI
builder.Services.AddAzureOpenAIChatCompletion(
deploymentName: builder.Configuration.GetSection("AIServices:AzureOpenAI").GetValue("DeploymentName"),
endpoint: builder.Configuration.GetSection("AIServices:AzureOpenAI").GetValue("Endpoint"),
//Use the Azure CLI (for local) or Managed Identity (for Azure running app) to authenticate to the Azure OpenAI service
credentials: new DefaultAzureCredential());

builder.Services.AddTransient((sp) =>
{
return new ChatCompletionAgent()
{
Name = AgentName,
Instructions = AgentInstructions,
Kernel = sp.GetRequiredService(),
Arguments = new KernelArguments(new OpenAIPromptExecutionSettings()
{
FunctionChoiceBehavior = FunctionChoiceBehavior.Auto(),
ResponseFormat = "json_object"
})

};

});

// Register IStorage. For development, MemoryStorage is suitable.
// For production Agents, persisted storage should be used so
// that state survives Agent restarts, and operate correctly
// in a cluster of Agent instances.
builder.Services.AddSingleton<IStorage, MemoryStorage>();

var app = builder.Build();

app.MapGet("/", () => "Hello Agent!");

app.UseStaticFiles();

app.UseDeveloperExceptionPage();

app.MapControllers();//.AllowAnonymous();

app.Run();

///

/// Creates an MCP client and connects it to the MCPServer server.
///

/// An instance of .
static Task CreateSSeMcpClientAsync(string mcpServerUrl)
{

return McpClientFactory.CreateAsync(new SseClientTransport(new()
{
    Name = "MCPServer",

    // Point the client to the MCPServer server executable
    Endpoint = new Uri(mcpServerUrl),
}));

}

static async Task AddTools(string mcpServerUrl, IKernelBuilder kernelBuilder)
{
IMcpClient mcpClient = await CreateSSeMcpClientAsync(mcpServerUrl);

IList<McpClientTool> tools = await mcpClient.ListToolsAsync();

kernelBuilder.Plugins.AddFromFunctions("Tools", tools.Select(aiFunction => aiFunction.AsKernelFunction()));

//// Enable automatic function calling
//OpenAIPromptExecutionSettings executionSettings = new()
//{
//    Temperature = 0,
//    FunctionChoiceBehavior = FunctionChoiceBehavior.Auto(options: new() { RetainArgumentTypes = true })
//};

}`