MCP Streamable HTTP 样例（qbit）

前言

模型上下文协议（Model Context Protocol，MCP），是由Anthropic推出的开源协议，旨在实现大语言模型与外部数据源和工具的集成，用来在大模型和数据源之间建立安全双向的连接。
本文代码技术栈
```
Python   3.11.8
FastMCP  2.10.3
```

MCP 的传输机制

Standard Input/Output (stdio)
Streamable HTTP
Server-Sent Events (SSE)（已被官方弃用）
本文使用 stdio 和 Streamable HTTP

FastMCP stdio 示例

MCP Server 代码 stdio_server.py

from fastmcp import FastMCP

mcp = FastMCP(name="StdioServer")

@mcp.tool
def hello(name: str) -> str:
    return f"Hello, {name}!"

@mcp.tool
def add(a: int, b: int) -> int:
    """Add two numbers"""
    return a + b

@mcp.tool
def multiply(a: float, b: float) -> float:
    """Multiplies two numbers."""
    return a * b

if __name__ == "__main__":
    mcp.run(transport="stdio")

MCP Client 代码 stdio_client.py

import asyncio
from fastmcp import Client
from fastmcp.client.transports import StdioTransport

transport = StdioTransport(
    command="D:/Python3Project/test_mcp/.venv/Scripts/python.exe", 
    args=["D:/Python3Project/test_mcp/stdio_server.py"]
)

async def main():
    async with Client(transport) as client:
        tools = await client.list_tools()
        print(f"Available tools: {tools}")
        result = await client.call_tool("add", {"a": 5, "b": 3})
        print(f"Result: {result}")


if __name__ == "__main__":
    asyncio.run(main())

stdio 模式下，由 client 启动 server，不用单独运行 server，Windows cmd 运行结果如下，注意用其他终端可能报错 RuntimeError: Client failed to connect: Connection closed

Available tools: [Tool(name='hello', title=None, description=None, inputSchema={'properties': {'name': {'title': 'Name', 'type': 'string'}}, 'required': ['name'], 'type': 'object'}, outputSchema={'properties': {'result': {'title': 'Result', 'type': 'string'}}, 'required': ['result'], 'title': '_WrappedResult', 'type': 'object', 'x-fastmcp-wrap-result': True}, annotations=None, meta=None), Tool(name='add', title=None, description='Add two numbers', inputSchema={'properties': {'a': {'title': 'A', 'type': 'integer'}, 'b': {'title': 'B', 'type': 'integer'}}, 'required': ['a', 'b'], 'type': 'object'}, outputSchema={'properties': {'result': {'title': 'Result', 'type': 'integer'}}, 'required': ['result'], 'title': '_WrappedResult', 'type': 'object', 'x-fastmcp-wrap-result': True}, annotations=None, meta=None), Tool(name='multiply', title=None, description='Multiplies two numbers.', inputSchema={'properties': {'a': {'title': 'A', 'type': 'number'}, 'b': {'title': 'B', 'type': 'number'}}, 'required': ['a', 'b'], 'type': 'object'}, outputSchema={'properties': {'result': {'title': 'Result', 'type': 'number'}}, 'required': ['result'], 'title': '_WrappedResult', 'type': 'object', 'x-fastmcp-wrap-result': True}, annotations=None, meta=None)]
Result: CallToolResult(content=[TextContent(type='text', text='8', annotations=None, meta=None)], structured_content={'result': 8}, data=8, is_error=False)

Postman 测试截图

MCP Streamable HTTP 样例（qbit）

前言

MCP 的传输机制

FastMCP stdio 示例

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