📌Overview

Purpose: To provide a C# SDK implementation of the Model Context Protocol (MCP) that facilitates communication between tools and applications.

Overview: ModelContextProtocol.NET is an SDK designed to create and manage servers compliant with the Model Context Protocol. It supports standard input/output communication and allows for easy tool integration through a structured architecture.

Key Features:

Standard I/O Communication: Facilitates seamless data exchange through standard input and output, ensuring compatibility across platforms.
Tool Integration Framework: Allows developers to implement and integrate custom tools within the MCP framework, enhancing functionality and usability.
Native AOT Compatible: Supports Native Ahead-Of-Time (AOT) compilation, enabling better performance and smaller binaries for applications.
Calculator Demo Implementation: Provides a fully functional calculator demo that showcases practical implementation of features, including logging, request handling, and error management.

ModelContextProtocol.NET

A C# SDK implementation of the Model Context Protocol (MCP).

Features

Ready to Use

Standard I/O Communication
Tool Integration Framework
Native AOT Compatible
Calculator Demo Implementation

Under Development

WebSocket Support
Resource Management
Prompt System

Demo

Refer to src/ModelContextProtocol.NET.Demo.Calculator for a fully functional calculator demo covering:

Logging setup
Tool handler implementation
Request/response handling
Error management

Getting Started

Install the server package:

dotnet add package ModelContextProtocol.NET.Server --prerelease

For hosting integration, add the server hosting package:

dotnet add package ModelContextProtocol.NET.Server.Hosting --prerelease

A. Without Hosting

// Create server info
var serverInfo = new Implementation { Name = "Calculator Demo Server", Version = "1.0.0" };

// Configure and build server
var builder = new McpServerBuilder(serverInfo).AddStdioTransport();
builder.Services.AddLogging(<see below>);
builder.Tools.AddHandler<YourToolHandler>();
builder.Tools.AddFunction(
    name: "YourToolName",
    description: "YourToolDescription",
    parameterTypeInfo: YourParameterTypeJsonContext.Default.YourParameterType,
    handler: (YourParameterType parameters, CancellationToken ct) => {
        // Your tool implementation
    }
);
// ...

var server = builder.Build();
server.Start();
await Task.Delay(-1); // Wait indefinitely

B. With Hosting

var builder = Host.CreateApplicationBuilder();
builder.Services.AddMcpServer(serverInfo, mcp => {
    mcp.AddStdioTransport();
    // same as without hosting
}, keepDefaultLogging: false); // clear default console logging
// ...

var host = builder.Build();
await host.RunAsync();

Logging Configuration

McpServerBuilder uses Microsoft.Extensions.Logging.ILogger as the logging interface.

When stdio transport is used, logs cannot be sent to the console. Configure a logging provider that writes to other destinations.

If no logging provider is configured, a null logger will be used, resulting in no logs.

The generic host builder adds console-based logger by default (ILoggerFactory and ILogger<T>). AddMcpServer removes them by default for the same reason.

To keep console logging, set keepDefaultLogging to true in AddMcpServer.

// Using Serilog
.ConfigureLogging(logging => logging.AddSerilog(yourSerilogLogger))

// Using NLog
.ConfigureLogging(logging => logging.AddNLog())

Implementing Tools

Tools are implemented as handlers.

For NativeAOT compatibility, a JsonTypeInfo is required for the parameter type.

You can either implement a handler class to benefit from dependency injection or supply a function directly.

More documentation and implementation guides coming soon.

Technical Details

Architecture

The project consists of several components:

Core Library: Fundamental protocol implementation
Server Components: Communication and request processing
Server Hosting: Integration of MCP server with .NET generic host
Demo: Working examples including a calculator application

Development Status

The project is actively developed. Core features like stdio communication and tool integration are complete and usable. Advanced features are under development.

Contributing

Contributions are welcome! Submit pull requests or create issues for bugs and feature requests.

License

Apache 2.0

ModelContextProtocol-NET