afrise/MCPSharp

MCPSharp is a .NET library that helps you build Model Context Protocol (MCP) servers and clients - the standardized API protocol used by AI assistants and models. With MCPSharp, you can:
Create MCP-compliant tools and functions that AI models can discover and use
Connect directly to existing MCP servers from C# code with an easy to use client
Expose your .NET methods as MCP endpoints with simple attributes
Handle MCP protocol details and JSON-RPC communication seamlessly
## 🚀 What's New in MCPSharp
Microsoft.Extensions.AI Integration: MCPSharp now integrates with Microsoft.Extensions.AI, allowing tools to be exposed as AIFunctions
Semantic Kernel Support: Add tools using Semantic Kernel's KernelFunctionAttribute
Dynamic Tool Registration: Register tools on-the-fly with custom implementation logic
Tool Change Notifications: Server now notifies clients when tools are added, updated, or removed
Complex Object Parameter Support: Better handling of complex objects in tool parameters
Better Error Handling: Improved error handling with detailed stack traces
## When to Use MCPSharp
Use MCPSharp when you want to:
Create tools that AI assistants like Anthropic's Claude Desktop can use
Build MCP-compliant APIs without dealing with the protocol details
Expose existing .NET code as MCP endpoints
Add AI capabilities to your applications through standardized interfaces
Integrate with Microsoft.Extensions.AI and/or Semantic Kernel without locking into a single vendor
## Features
Easy-to-use attribute-based API ([McpTool], [McpResource])
Built-in JSON-RPC support with automatic request/response handling
Automatic parameter validation and type conversion
Rich documentation support through XML comments
Near zero configuration required for basic usage
## Prerequisites
Any version of .NET that supports standard 2.0
## Installation
bash
dotnet add package MCPSharp
## Quick Start
### 1. Define a Tool
Create a class and mark your method(s) with the [McpTool] attribute:
csharp
using MCPSharp;
public class Calculator
[McpTool("add", "Adds two numbers")] // Note: [McpFunction] is deprecated, use [McpTool] instead
public static int Add([McpParameter(true)] int a, [McpParameter(true)] int b)
return a + b;
### 2. Start the Server
csharp
await MCPServer.StartAsync("CalculatorServer", "1.0.0");
The StartAsync() method will automatically find any methods in the base assembly that are marked with the McpTool attribute. In order to add any methods that are in a referenced library, you can manually register them by calling MCPServer.Register (); with T being the class containing the desired methods. If your methods are marked with Semantic Kernel attributes, this will work as well. If the client supports list changed notifications, it will be notified when additional tools are registered.
## Advanced Usage
### Dynamic Tool Registration
Register tools dynamically with custom implementation:
csharp
MCPServer.AddToolHandler(new Tool()
Name = "dynamicTool",
Description = "A dynamic tool",
InputSchema = new InputSchema {
Type = "object",
Required = ["input"],
Properties = new Dictionary {
{"input", new ParameterSchema{Type="string", Description="Input value"}}