afrise/MCPSharp

dotnet add package MCPSharp

Usage

• •Mark methods with [McpTool("name", "description")] and [McpParameter(true)] for required params
• •await MCPServer.StartAsync("CalculatorServer", "1.0.0"); // auto-discovers [McpTool] methods in base assembly
• •Register referenced-library classes: MCPServer.Register<T>(); // also works with Semantic Kernel KernelFunctionAttribute
• •Client use: MCPClient client = new("AI", "1.0", "path/to/server"); IList<AIFunction> fns = await client.GetFunctionsAsync();

Key features

• ✓Attribute-based API: [McpTool], [McpParameter], [McpResource] (name, uri with templates, mimeType)
• ✓Built-in JSON-RPC request/response handling, automatic parameter validation and type conversion
• ✓Microsoft.Extensions.AI integration (tools exposed as AIFunctions usable with any IChatClient) and Semantic Kernel support
• ✓Dynamic tool registration (MCPServer.AddToolHandler), tool change notifications to clients, complex object parameter support
• ✓XML documentation auto-extracted into tool docs (change names/descriptions without recompiling)

Best for

.NET/C# developers who want to expose existing methods as MCP endpoints or connect to MCP servers from C# code without dealing with protocol details.

Caveats

• ⚠[McpFunction] is deprecated — use [McpTool]; MCPServer.RegisterTool<T>() deprecated in favor of MCPServer.Register<T>()
• ⚠Semantic Kernel integration currently only via MCPServer.Register<T>() (no kernel-wide introspection)