My MCP Server is not discovering my custom tools

1 week ago 18

ARTICLE AD BOX

I have a stdio mcp server running locally. The mcp server builds and runs. I have created 3 basic mcp tools that I will use for context when I prompt in Copilot however my tools are just not discoverable.

I do have the tools defined with the correct method attributes ie [McpServerTool]. I do have the modelcontextprotocol package installed (ModelContextProtocol version 0.4.0-preview.1) I have started the mcp server (dotnet build and dotnet run)

mcp.json

"servers": { "sfmd-mcp-server-v2": { "type": "stdio", "command": "dotnet", "args": [ "run", "--project", "C:/Sfmd-AI-Assist/sfmd-mcp-server-v2/sfmd-mcp-server-v2.csproj" ] } } }

Program.cs (taken from: https://developer.microsoft.com/blog/microsoft-partners-with-anthropic-to-create-official-c-sdk-for-model-context-protocol)

using Microsoft.Extensions.DependencyInjection; using Microsoft.Extensions.Hosting; using Microsoft.Extensions.Logging; using ModelContextProtocol.Server; using System.ComponentModel; var builder = Host.CreateApplicationBuilder(args); builder.Logging.AddConsole(consoleLogOptions => { // Configure all logs to go to stderr consoleLogOptions.LogToStandardErrorThreshold = LogLevel.Trace; }); builder.Services .AddMcpServer() .WithStdioServerTransport() .WithToolsFromAssembly(); await builder.Build().RunAsync(); [McpServerToolType] public static class EchoTool { [McpServerTool, Description("Echoes the message back to the client.")] public static string Echo(string message) => $"hello from C# Server: {message}"; [McpServerTool, Description("Echoes back the message in reverse.")] public static string Reverse(string message) => new string(message.Reverse().ToArray()); [McpServerTool, Description("Returns the length of the message.")] public static int Length(string message) => message.Length; }

The warning is not going away no matter what I do: