Model Context Protocol (MCP)

Learn the fundamentals of the Model Context Protocol and how it enables secure, standardized communication between AI models and external tools.

What is MCP?

The Model Context Protocol (MCP) is an open standard developed by Anthropic that provides a unified interface for AI assistants to interact with external data sources and tools. It acts as a bridge between AI models and the systems they need to work with.

Core Concepts

1. Client-Server Architecture

MCP follows a client-server model where:

Clients - Applications that want to use tools (like AI assistants)
Servers - Services that provide tools and resources

2. Resources

Resources represent data that servers can expose to clients:

interface Resource {
  uri: string;          // Unique identifier
  name: string;         // Human-readable name
  description?: string; // Optional description
  mimeType?: string;    // Content type
}

3. Tools

Tools are functions that servers expose for clients to execute:

interface Tool {
  name: string;
  description?: string;
  inputSchema: {
    type: 'object';
    properties: Record<string, any>;
    required?: string[];
  };
}

4. Prompts

Prompts are reusable templates that help structure interactions:

interface Prompt {
  name: string;
  description?: string;
  arguments?: Array<{
    name: string;
    description?: string;
    required?: boolean;
  }>;
}

Protocol Messages

MCP uses JSON-RPC 2.0 for communication with these key message types:

Initialization

// Client → Server
{
  "jsonrpc": "2.0",
  "method": "initialize",
  "params": {
    "protocolVersion": "2024-11-05",
    "capabilities": {},
    "clientInfo": {
      "name": "my-app",
      "version": "1.0.0"
    }
  },
  "id": 1
}

Tool Execution

// Client → Server
{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "get_weather",
    "arguments": {
      "city": "San Francisco"
    }
  },
  "id": 2
}

Security Model

MCP includes built-in security features:

Capability negotiation - Servers only expose agreed-upon features
Schema validation - All inputs are validated against defined schemas
Transport security - Supports secure transports like HTTPS
Authentication - Optional auth mechanisms per transport

Lifecycle

A typical MCP session follows this lifecycle:

Connection - Client establishes transport connection
Initialization - Protocol version and capabilities negotiated
Discovery - Client lists available resources and tools
Interaction - Client calls tools and accesses resources
Termination - Clean shutdown of connection

Benefits

Standardization - One protocol for all integrations
Security - Built-in security considerations
Flexibility - Multiple transport options
Type Safety - Schema-based validation
Discoverability - Self-documenting tools and resources

Next Steps