mcp-architecture

MCP Architecture Skill

This skill provides comprehensive knowledge of the Model Context Protocol (MCP) specification, implementation patterns, and operational best practices.

MCP Architecture Overview

Client-Host-Server Model

┌─────────────────────────────────────────────────────────┐
│                        HOST                             │
│  (Claude Desktop, IDE Extension, AI Application)        │
│                                                         │
│   ┌─────────────┐    ┌─────────────┐                   │
│   │   Client A  │    │   Client B  │   (MCP Clients)   │
│   └──────┬──────┘    └──────┬──────┘                   │
└──────────┼──────────────────┼───────────────────────────┘
           │                  │
     ┌─────▼─────┐      ┌─────▼─────┐
     │  Server A │      │  Server B │    (MCP Servers)
     │ (Local)   │      │ (Remote)  │
     └───────────┘      └───────────┘

• Host: Application containing the LLM (Claude Desktop, IDE)
• Client: Protocol handler within the host, one per server connection
• Server: Exposes resources, tools, and prompts via MCP

Transport Protocols

Transport	Use Case	Characteristics
stdio	Local servers	Subprocess communication, simplest setup
Streamable HTTP	Remote servers	HTTP/SSE, supports auth, firewall-friendly
WebSocket	Bidirectional	Real-time, persistent connection

MCP Primitives

1. Resources (Data Exposure)

Resources expose data/content for the LLM to read. They are application-controlled (host decides when to include).

# Python (FastMCP)
from fastmcp import FastMCP

mcp = FastMCP("my-server")

@mcp.resource("config://app/settings")
def get_settings() -> str:
    """Application configuration settings."""
    return json.dumps(load_settings())

@mcp.resource("file://{path}")
def read_file(path: str) -> str:
    """Read a file from the workspace."""
    return Path(path).read_text()