MCP C++ SDK - Model Context Protocol Implementation for C++

The most comprehensive C++ implementation of the Model Context Protocol (MCP) for building AI-powered applications. Production-ready SDK with enterprise features including multi-transport support, connection pooling, and multi-language bindings via C API (Python, TypeScript, Go, Rust, Java, C#, Ruby and more).

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Table of Contents

• Architecture Overview
• Cross-Language Support
• What is MCP?
• Features
• Quick Start
• Examples
• Installation
• Documentation
• FAQ
• Contributing
• License

Architecture Overview

┌─────────────────────────────────────────────────────────────────────┐
│                         Application Layer                           │
│  ┌────────────────────────────────────────────────────────────────┐ │
│  │      MCP Server │ MCP Client │ Custom Applications             │ │
│  └────────────────────────────────────────────────────────────────┘ │
├─────────────────────────────────────────────────────────────────────┤
│                    Cross-Language Binding Layer                     │
│  ┌────────────────────────────────────────────────────────────────┐ │
│  │   Python │ TypeScript │ Go │ Rust │ Java │ C# │ Ruby │ Swift   │ │
│  └────────────────────────────────────────────────────────────────┘ │
├─────────────────────────────────────────────────────────────────────┤
│                          C API (FFI Layer)                          │
│  ┌────────────────────────────────────────────────────────────────┐ │
│  │   libgopher_mcp_c: Opaque Handles │ RAII Guards │ Type Safety  │ │
│  └────────────────────────────────────────────────────────────────┘ │
├─────────────────────────────────────────────────────────────────────┤
│                            Protocol Layer                           │
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ ┌────────────┐  │
│  │   JSON-RPC   │ │   Requests   │ │  Responses   │ │   Notify   │  │
│  │   Codec      │ │   Dispatch   │ │   Routing    │ │   Stream   │  │
│  └──────────────┘ └──────────────┘ └──────────────┘ └────────────┘  │
├─────────────────────────────────────────────────────────────────────┤
│                          Filter Chain Layer                         │
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ ┌────────────┐  │
│  │  HTTP / SSE  │ │   Routing    │ │ Rate Limiter │ │   Auth     │  │
│  │    Codecs    │ │   & CORS     │ │ Circuit Brk  │ │  Metrics   │  │
│  └──────────────┘ └──────────────┘ └──────────────┘ └────────────┘  │
├─────────────────────────────────────────────────────────────────────┤
│                           Transport Layer                           │
│  ┌────────────────────────────────────────────────────────────────┐ │
│  │   Stdio │ HTTP(S)+SSE │ Streamable HTTP │ WebSocket │ TCP      │ │
│  └────────────────────────────────────────────────────────────────┘ │
├─────────────────────────────────────────────────────────────────────┤
│                            Network Layer                            │
│  ┌────────────────┐ ┌────────────────┐ ┌────────────────┐           │
│  │   Connection   │ │    Listener    │ │     Socket     │           │
│  │   Management   │ │    & Accept    │ │   Interface    │           │
│  └────────────────┘ └────────────────┘ └────────────────┘           │
├─────────────────────────────────────────────────────────────────────┤
│                       Event Loop & Dispatcher                       │
│  ┌────────────────────────────────────────────────────────────────┐ │
│  │   Libevent │ Timer Management │ I/O Events │ Buffer │ Result   │ │
│  └────────────────────────────────────────────────────────────────┘ │
└─────────────────────────────────────────────────────────────────────┘

Design Principles

1. Thread-Safe Dispatcher Model - All I/O in dispatcher threads, no complex synchronization
2. Filter Chain Architecture - Modular, composable request processing
3. Production Patterns - Connection pooling, circuit breaker, graceful shutdown

Cross-Language Support

Use MCP C++ SDK from any programming language via the stable C API (libgopher_mcp_c):

# Installation paths
Headers: /usr/local/include/gopher-mcp/mcp/c_api/
Library: /usr/local/lib/libgopher_mcp_c.{so,dylib,dll}

What is MCP?

Model Context Protocol (MCP) is an open protocol that enables AI models (like Claude, GPT, etc.) to securely interact with external tools, data sources, and services. MCP provides a standardized way for:

• AI assistants to access files, databases, and APIs
• Developers to expose tools and resources to AI models
• Applications to integrate AI capabilities with enterprise systems

This MCP C++ SDK implements the official MCP specification in high-performance C++, suitable for:

• Embedded systems and IoT devices
• High-frequency trading and real-time applications
• Game engines and graphics applications
• Native desktop and mobile applications
• Backend services requiring low latency

Features

Quick Start

Build and Install

# Show all available commands
make help

# Build
make

# Install (auto-prompts for sudo if needed)
make install

# Run tests
make test

Create an MCP Server

#include "mcp/server/mcp_server.h"

int main() {
    mcp::server::McpServerConfig config;
    config.server_name = "my-mcp-server";

    auto server = mcp::server::createMcpServer(config);

    // Register a tool
    mcp::Tool calculator;
    calculator.name = "add";
    calculator.description = "Add two numbers";

    server->registerTool(calculator, [](const std::string& name,
                                         const mcp::optional<mcp::Metadata>& arguments,
                                         mcp::server::SessionContext& ctx) {
        mcp::CallToolResult result;
        auto args = arguments.value();
        auto a_it = args.find("a");
        auto b_it = args.find("b");

        double a = mcp::holds_alternative<double>(a_it->second)
                       ? mcp::get<double>(a_it->second) : 0.0;
        double b = mcp::holds_alternative<double>(b_it->second)
                       ? mcp::get<double>(b_it->second) : 0.0;

        result.content.push_back(mcp::TextContent{"Result: " + std::to_string(a + b)});
        return result;
    });

    server->listen("http://0.0.0.0:3000");
    server->run();
}

Create an MCP Client

#include "mcp/client/mcp_client.h"

int main() {
    mcp::client::McpClientConfig config;
    config.client_name = "my-mcp-client";

    auto client = mcp::client::createMcpClient(config);
    client->connect("http://localhost:3000");

    // Initialize protocol
    auto init = client->initializeProtocol().get();

    // Call a tool
    auto args = mcp::make<mcp::Metadata>()
                    .add("a", 10.0)
                    .add("b", 5.0)
                    .build();

    auto result = client->callTool("add", mcp::make_optional(args)).get();
}

Examples

See examples/mcp/README.md for complete working examples:

# Terminal 1: Start server
./build/examples/mcp/mcp_example_server --verbose

# Terminal 2: Run client with demo
./build/examples/mcp/mcp_example_client --demo --verbose

The example server includes:

• Resource registration and subscriptions
• Tool execution (calculator, database query, system info)
• Prompt templates
• Session management
• HTTP/SSE endpoints

Installation

Prerequisites

• C++14 compiler (GCC 8+, Clang 10+, MSVC 2019+)
• CMake 3.10+
• libevent 2.1+
• OpenSSL 1.1+ (optional, for TLS)

Build Options

# Debug build
make debug

# Release build
make release

# Static libraries only
cmake -B build -DBUILD_SHARED_LIBS=OFF

# Without C API
cmake -B build -DBUILD_C_API=OFF

# Custom install prefix
cmake -B build -DCMAKE_INSTALL_PREFIX=~/.local

Windows (Cygwin + MinGW)

Building on Windows requires Cygwin with MinGW-w64 toolchain:

Prerequisites

Install Cygwin with these packages:

• make, cmake - Build tools
• mingw64-x86_64-gcc-g++ - Mi