mcpsdk 0.1.2

The simplest way to build and connect MCP servers and clients.

MCPSDK

The simplest way to build and connect MCP (Model Context Protocol) servers and clients in Python.

No async. No boilerplate. Just define your tools and go.

Install

pip install mcpsdk

Quickstart

Build a server

from mcpsdk import MCPServer

server = MCPServer("my-server")

@server.tool
def get_weather(city: str) -> str:
    """Get the current weather for a city."""
    return f"Sunny in {city}, 22C"

@server.tool
def calculate(expression: str) -> str:
    """Evaluate a math expression."""
    return str(eval(expression))

server.run()              # stdio (default)
server.run(mode="sse")    # SSE on http://0.0.0.0:8000

Connect a client

from mcpsdk import MCPClient

# SSE — server already running
with MCPClient.from_sse("http://localhost:8000/sse") as client:
    tools  = client.list_tools()
    result = client.call_tool("get_weather", {"city": "Tokyo"})
    print(result)

# stdio — client spawns the server
with MCPClient.from_stdio("python", ["server.py"]) as client:
    tools  = client.list_tools()
    result = client.call_tool("calculate", {"expression": "12 * 7"})
    print(result)

Use with any LLM

list_tools() returns raw MCP format — convert to your LLM's format yourself:

from mcpsdk import MCPClient

with MCPClient.from_sse("http://localhost:8000/sse") as client:
    tools = client.list_tools()
    # tools → [{ "name", "description", "parameters" }]

    # Anthropic
    anthropic_tools = [{"name": t["name"], "description": t["description"], "input_schema": t["parameters"]} for t in tools]

    # OpenAI
    openai_tools = [{"type": "function", "function": {"name": t["name"], "description": t["description"], "parameters": t["parameters"]}} for t in tools]

    # when LLM picks a tool:
    result = client.call_tool(tool_name, params)

API

MCPServer

Method	Description
MCPServer(name)	Create a server
@server.tool	Register a function as a tool
server.run(mode, host, port)	Start the server (mode="stdio" or "sse")

MCPClient

Method	Description
MCPClient.from_sse(url)	Create client for remote SSE server
MCPClient.from_stdio(command, args)	Create client for local stdio server
client.connect()	Open connection
client.disconnect()	Close connection
client.list_tools()	Get all tools from server
client.call_tool(name, params)	Call a tool, get result as string
client.tool_info(name)	Get details of one tool

Transport modes

	stdio	SSE
Where	Same machine	Anywhere
Server startup	Client spawns it	Already running
Connect with	from_stdio(cmd, args)	from_sse(url)
Best for	Local tools	Remote / shared servers

License

MIT