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

Architecture

┌─────────────────────────────────────────────────────────────┐
│                     Application Layer                       │
│         MCP Server / Client / Custom Applications           │
├─────────────────────────────────────────────────────────────┤
│              Cross-Language Binding Layer                   │
│      Python │ TypeScript │ Go │ Rust │ Java │ C# │ Ruby     │
├─────────────────────────────────────────────────────────────┤
│                    C API (FFI Layer)                        │
│       libgopher_mcp_c: Opaque Handles │ Memory Safety       │
│        RAII Guards │ Type Safety │ Error Handling           │
├─────────────────────────────────────────────────────────────┤
│                      Protocol Layer                         │
│           MCP JSON-RPC Protocol Implementation              │
│          Request/Response/Notification Handling             │
├─────────────────────────────────────────────────────────────┤
│                    Filter Chain Layer                       │
│      HTTP Codec │ SSE Codec │ Routing │ Rate Limiting       │
│      Circuit Breaker │ Metrics │ Backpressure │ Auth        │
├─────────────────────────────────────────────────────────────┤
│                    Transport Layer                          │
│      Stdio │ HTTP(s)+SSE │ WebSocket │ TCP │ Redis │ P2P    │
├─────────────────────────────────────────────────────────────┤
│                     Network Layer                           │
│      Connection Management │ Listener │ Socket Interface    │
├─────────────────────────────────────────────────────────────┤
│                  Event Loop & Dispatcher                    │
│      Libevent Integration │ Timer Management │ I/O Events   │
└─────────────────────────────────────────────────────────────┘

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):

| Language | Binding Type | Features | |----------|--------------|----------| | Python | ctypes/cffi | Async support, type hints | | TypeScript/Node.js | N-API | High performance, native async | | Go | CGO | Goroutine-safe wrappers | | Rust | FFI | Safe wrappers, ownership guarantees | | Java | JNI | Automatic resource management | | C#/.NET | P/Invoke | Async/await support | | Ruby | Native extension | GC integration |

# 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

| Category | Features | |----------|----------| | Protocol | Full MCP 2025-06-18 specification, JSON-RPC 2.0, resources, tools, prompts | | Transports | stdio, HTTP+SSE, HTTPS+SSE, WebSocket, TCP | | Performance | Zero-copy buffers, lock-free operations, connection pooling | | Reliability | Circuit breaker, rate limiting, retry with backoff, graceful shutdown | | Security | TLS/SSL, authentication middleware, request validation | | Observability | Structured logging, metrics, health endpoints | | Cross-Language | C API for Python, Node.js, Go, Rust, Java, C#, Ruby bindings |

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++ - MinGW C++ compiler
• mingw64-x86_64-libevent - Event library
• mingw64-x86_64-openssl - SSL/TLS library

Build Commands

# From Cygwin bash shell
./build-mingw.sh           # Release build (default)
./build-mingw.sh debug     # Debug build
./build-mingw.sh release   # Release build
./build-mingw.sh clean     # Clean build directory

Output

• Build directory: build-mingw/
• Executable: build-mingw/examples/mcp/mcp_example_server.exe

Documentation

MCP C++ Documentation

• Examples Guide - Working server and client examples

MCP CPP Core Components

• MCP Protocol in C++ - Model Context Protocol implementation details
• Filter Chain - Processing pipeline architecture
• Transport Layer - Transport implementations
• Network Layer - Connection management and socket abstraction

Design Documents

• Event Loop Design - Event-driven architecture and dispatcher design
• Filter Usage Guide - Comprehensive guide for using and creating filters
• CTAD Alternatives - Class Template Argument Deduction alternatives for C++14
• MCP Serialization Coverage - JSON serialization implementation details

FAQ