N2.McpCore

A .NET library providing core abstractions and utilities for implementing Model Context Protocol (MCP) servers. This package enables you to build MCP-compliant servers that can integrate with AI assistants and other MCP clients.

Features

• Multi-Framework Support: Targets .NET Standard 2.0, .NET Standard 2.1, .NET 8.0, and .NET 9.0
• JSON-RPC 2.0 Implementation: Complete JSON-RPC protocol support for request/response handling
• MCP Protocol Compliance: Implements MCP specification version "2024-11-05"
• Extensible Architecture: Base classes and interfaces for easy server implementation
• Type-Safe Models: Strongly-typed protocol models with JSON serialization support
• Tool Framework: Built-in support for defining and executing MCP tools

Installation

Install via NuGet Package Manager:

dotnet add package N2.Core.Abstractions

Or via Package Manager Console:

Install-Package N2.Core.Abstractions

Quick Start

1. Create a Custom MCP Server

using McpCore.Server;
using McpCore.Protocol;

public class MyMcpServer : McpServer
{
    public MyMcpServer() : base(
        new McpServerInfo
        {
            Name = "my-server",
            Version = "1.0.0"
        },
        new McpServerCapabilities
        {
            Tools = new McpToolsCapability()
        })
    {
    }

    protected override McpTool[] GetAvailableTools()
    {
        return new[]
        {
            new McpTool
            {
                Name = "get_weather",
                Description = "Get current weather for a location",
                InputSchema = new McpInputSchema
                {
                    Type = "object",
                    Properties = new Dictionary<string, McpPropertyDefinition>
                    {
                        ["location"] = new McpPropertyDefinition
                        {
                            Type = "string",
                            Description = "City name"
                        }
                    },
                    Required = new[] { "location" }
                }
            }
        };
    }

    protected override async Task<McpToolCallResult> CallToolAsync(McpToolCallParams parameters)
    {
        if (parameters.Name == "get_weather")
        {
            var location = parameters.Arguments["location"]?.ToString();
            // Implement your tool logic here
            return new McpToolCallResult
            {
                Content = new[]
                {
                    new McpContent
                    {
                        Type = "text",
                        Text = $"Weather in {location}: Sunny, 72°F"
                    }
                }
            };
        }

        throw new ArgumentException($"Unknown tool: {parameters.Name}");
    }
}

2. Process JSON-RPC Requests

var server = new MyMcpServer();

// Handle incoming JSON-RPC request
var request = new JsonRpcRequest
{
    Id = 1,
    Method = "tools/list",
    Params = null
};

var response = await server.ProcessRequestAsync(request);

Architecture

The library is organized into three main components:

• JsonRpc: JSON-RPC 2.0 protocol implementation with request/response/error models
• Protocol: MCP-specific protocol models including initialization, tools, and capabilities
• Server: Base server implementation with extensible method handlers

MCP Server Lifecycle

1. Initialize: Client sends initialize request with capabilities
2. Initialized: Client sends initialized notification to complete handshake
3. Ready: Server can now handle tools/list and tools/call requests

For detailed architecture documentation, see CLAUDE.md.

Configuration

The library includes flexible configuration utilities through N2ConfigurationExtensions:

// Check if a feature is enabled from IConfiguration
bool isEnabled = configuration.HasFeature("MyFeature");

Supported configuration formats:

• Boolean flags: Features:MyFeature = true
• CSV strings: Features = "FeatureA,FeatureB"
• String arrays: Features = ["FeatureA", "FeatureB"]

Building from Source

# Clone the repository
git clone https://github.com/kaalenco/n2-mcp-core.git
cd n2-mcp-core

# Build the solution
dotnet build src/N2.McpCore.sln

# Build for release
dotnet build src/N2.McpCore.sln -c Release

Contributing

Contributions are welcome! Please ensure:

• Code follows existing architectural patterns
• All code analysis warnings are addressed (warnings are treated as errors)
• XML documentation is provided for public APIs
• Changes are tested across all target frameworks

License

This project is licensed under the Academic Free License v3.0 (AFL-3.0). See LICENSE for details.

Copyright (c) 2025 Kaalenco - All rights reserved

Links

• Model Context Protocol Specification
• Package on NuGet
• Project Repository