Model Context Protocol Cheatsheet: Tools, Resources and Sampling Reference

# Python SDK (FastMCP) — recommended for new servers
pip install "mcp[cli]"

# Run a server (stdio transport — Claude Desktop default)
mcp dev server.py                # interactive inspector
mcp install server.py            # register with Claude Desktop

# TypeScript SDK
npm install @modelcontextprotocol/sdk

# Pick a transport
#   stdio   - desktop apps, subprocess-style
#   http    - streamable HTTP, web hosts
#   sse     - legacy server-sent events (deprecated 2025-03)

// 1 — client → server
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "initialize",
  "params": {
    "protocolVersion": "2025-06-18",
    "capabilities": {
      "roots":    { "listChanged": true },
      "sampling": {}
    },
    "clientInfo": { "name": "ExampleClient", "version": "1.0.0" }
  }
}

// 2 — server → client
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "protocolVersion": "2025-06-18",
    "capabilities": {
      "tools":     { "listChanged": true },
      "resources": { "listChanged": true, "subscribe": true },
      "prompts":   { "listChanged": true },
      "logging":   {}
    },
    "serverInfo": { "name": "ExampleServer", "version": "0.3.1" }
  }
}

// 3 — client → server (must follow before any other request)
{ "jsonrpc": "2.0", "method": "notifications/initialized" }

from mcp.server.fastmcp import FastMCP
from pydantic import Field

mcp = FastMCP("Weather")

@mcp.tool()
def get_forecast(
    city: str = Field(..., description="City name, English"),
    units: str = Field("metric", description="metric | imperial"),
) -> dict:
    """Return the next-48h forecast for the given city."""
    return fetch_forecast(city, units)

@mcp.resource("weather://stations")
def list_stations() -> str:
    """Static directory of weather stations as Markdown."""
    return load_stations_markdown()

@mcp.prompt()
def daily_briefing(city: str) -> str:
    """Prompt template — caller substitutes {city}."""
    return f"Give me a 3-line weather briefing for {city}."

if __name__ == "__main__":
    mcp.run()  # stdio by default; mcp.run(transport="http") for HTTP

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";

const server = new McpServer({ name: "weather", version: "0.1.0" });

server.tool(
  "get_forecast",
  "Next-48h forecast for a city.",
  {
    city:  z.string().describe("City name, English"),
    units: z.enum(["metric", "imperial"]).default("metric"),
  },
  async ({ city, units }) => ({
    content: [{ type: "text", text: await fetchForecast(city, units) }],
  }),
);

server.resource("stations", "weather://stations", async () => ({
  contents: [{ uri: "weather://stations", text: await loadStations() }],
}));

await server.connect(new StdioServerTransport());

// claude_desktop_config.json
// macOS:   ~/Library/Application Support/Claude/claude_desktop_config.json
// Windows: %APPDATA%\Claude\claude_desktop_config.json
{
  "mcpServers": {
    "weather": {
      "command": "uv",
      "args": ["--directory", "/Users/me/code/weather", "run", "server.py"],
      "env": { "WEATHER_API_KEY": "..." }
    },
    "filesystem": {
      "command": "npx",
      "args": [
        "-y", "@modelcontextprotocol/server-filesystem",
        "/Users/me/Documents"
      ]
    }
  }
}

from mcp.server.fastmcp import FastMCP
from pydantic import Field

mcp = FastMCP("Weather")

@mcp.tool()
def get_forecast(
    city: str = Field(..., description="City name, English"),
    units: str = Field("metric", description="metric | imperial"),
) -> dict:
    """Return the next-48h forecast for the given city."""
    return fetch_forecast(city, units)

@mcp.resource("weather://stations")
def list_stations() -> str:
    """Static directory of weather stations as Markdown."""
    return load_stations_markdown()

@mcp.prompt()
def daily_briefing(city: str) -> str:
    """Prompt template — caller substitutes {city}."""
    return f"Give me a 3-line weather briefing for {city}."

if __name__ == "__main__":
    mcp.run()  # stdio by default; mcp.run(transport="http") for HTTP