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MCP Framework Implementation Summary

Overview

This implementation provides a complete C++ framework for the Model Context Protocol (MCP), designed for easy extension to agent workflows. The framework follows a modular architecture with clear separation of concerns, making it straightforward to customize and extend.

Directory Structure

/MCP/
├── mcp_protocol.h/cpp      - Core protocol definitions
├── mcp_server.h/cpp        - Server implementation
├── mcp_client.h/cpp        - Client implementation
├── mcp_resource.h          - Resource definitions
├── mcp_tools.h/cpp         - Tool and workflow system implementation
├── mcp_workflow_resource.h/cpp - Workflow resource implementation
├── mcp_agent_resource.cpp  - Agent resource implementation
├── CMakeLists.txt          - Build system configuration
├── README.md               - Project documentation
└── examples/               - Example implementations
    ├── custom_agent.h/cpp  - Custom agent implementations
    ├── server_example.cpp  - Server example
    ├── client_example.cpp  - Client example
    └── host_example.cpp    - Host example

Key Components

1. Core Protocol (mcp_protocol.h/cpp)

Defines the fundamental structures of the MCP protocol:

request and response structures
Error handling with error_code and mcp_exception
Resource interface (resource base class)
Tool definition structure (tool)

2. Server (mcp_server.h/cpp)

Provides an HTTP server that exposes MCP resources and tools:

Register resources at specific paths
Register tools with handlers
Process incoming HTTP requests
Route requests to appropriate resources

3. Client (mcp_client.h/cpp)

Implements a client for connecting to MCP servers:

Connect to servers
Discover available resources and tools
Make requests to resources
Call tools with parameters

4. Resource System (mcp_resource.h)

Defines various resource types:

file_resource: Access to the file system
directory_resource: Directory operations
api_resource: Custom API endpoints
image_resource: Image handling

5. Tool System (mcp_tools.h/cpp) - New Implementation

Provides tool-related functionality:

tool_registry: Central registry for tools
tool_builder: Fluent API for tool creation
workflow_step: Single step in a workflow
workflow: Define and execute sequences of tool calls
agent: Base class for agents

6. Workflow Resources (mcp_workflow_resource.h/cpp, mcp_agent_resource.cpp) - New Implementation

Implements resources for workflow and agent management:

workflow_resource: Create, manage, and execute workflows
agent_resource: Register and manage agents

Usage Examples

1. Creating a Server

// Create and configure the server
mcp::server server("localhost", 8080);
server.set_name("Example Server");

// Register a tool
mcp::tool time_tool = mcp::tool_builder("get_time")
    .with_description("Get the current time")
    .build();

server.register_tool(time_tool, get_time_handler);

// Register a resource
auto file_resource = std::make_shared<mcp::file_resource>("./files");
server.register_resource("/files", file_resource);

// Start the server
server.start(true);

2. Connecting with a Client

// Create a client
mcp::client client("localhost", 8080);

// Call a tool
mcp::json result = client.call_tool("get_time");

// Make a request to a resource
mcp::response res = client.get("/files/example.txt");

3. Creating and Using Workflows

// Create a workflow
mcp::workflow workflow("data_processing", "Process data");

// Add steps
workflow.add_tool_call("get_data", {{"source", "database"}});
workflow.add_tool_call("process_data", {{"filter", "recent"}});

// Execute the workflow
mcp::json result = workflow.execute();

4. Implementing Custom Agents

// Create a custom agent
class custom_agent : public mcp::agent {
public:
    explicit custom_agent(const std::string& name) : mcp::agent(name) {}
    
    void initialize(const mcp::json& config) override {
        // Initialize from config
    }
    
    mcp::json process(const mcp::json& input) override {
        // Process the input
        mcp::json output = call_tool("some_tool", input);
        return output;
    }
};

Agent Workflow Extension

The framework is specifically designed to support agent workflows with:

Workflow Engine: Define sequences of tool calls with data passing
Agent Base Class: Easily create custom agents
Tool Registry: Centralized tool management
Resource APIs: RESTful interfaces for workflow and agent management

Custom Agent Examples

Three example agent implementations are provided:

Echo Agent: Simple agent that echoes back input with optional processing
Workflow Agent: Executes predefined workflows
Chain Agent: Chains multiple tools together with data mapping

Host Integration

The host example demonstrates how to:

Combine server and client functionality
Manage connections to other MCP servers
Create workflows that span multiple servers
Register and manage agents

Building the Project

Use the provided CMakeLists.txt:

mkdir build && cd build
cmake ..
make

Extending the Framework

Adding New Tools

// Define a new tool
mcp::tool my_tool = mcp::tool_builder("my_tool")
    .with_description("My custom tool")
    .with_string_param("input", "Input string")
    .build();

// Implement the tool handler
mcp::json my_tool_handler(const mcp::json& params) {
    std::string input = params["input"];
    // Process the input
    return {{"output", "Processed: " + input}};
}

// Register with the server
server.register_tool(my_tool, my_tool_handler);

Creating New Resource Types

class custom_resource : public mcp::resource {
public:
    resource_type type() const override {
        return resource_type::custom;
    }
    
    json metadata() const override {
        return {{"name", "Custom Resource"}};
    }
    
    response handle_request(const request& req) override {
        // Handle the request
        response res;
        res.set_json_body({{"status", "success"}});
        return res;
    }
};

Implementing New Agent Types

class my_agent : public mcp::agent {
public:
    explicit my_agent(const std::string& name) : mcp::agent(name) {}
    
    void initialize(const mcp::json& config) override {
        // Initialize from config
    }
    
    mcp::json process(const mcp::json& input) override {
        // Custom processing logic
        return result;
    }
};

Conclusion

This MCP Protocol framework provides a robust foundation for building agent-based systems. It offers:

Standardized Communication: Common protocol for all components
Extensible Design: Easy to add new tools, resources, and agents
Workflow Support: Define and execute complex workflows
Agent Framework: Create specialized agents for different tasks

The implementation uses lower_line_naming_style as requested and provides comprehensive examples of customized host, client, and server configurations.

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