什么是MCP？
MCP（Model Context Protocol）是一个开放的协议标准，用于连接AI助手（如Claude、GPT等）与外部工具和数据源。它定义了一套标准化的通信方式，让AI助手能够安全、可靠地调用外部服务。
MCP的核心概念
1. 客户端-服务器架构
- 客户端：AI助手（如Claude Desktop、VS Code插件等）
- 服务器：提供工具和资源的外部服务
- 通信方式：通过标准输入输出进行JSON-RPC 2.0协议通信
2. 传输协议
- 使用JSON-RPC 2.0作为通信协议
- 通过stdin/stdout进行数据传输
- 每行一个JSON对象，以换行符分隔
MCP基本语法规范
1. 初始化请求initialize
{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{"tools":{}},"clientInfo":{"name":"Claude Desktop","version":"1.0.0"}}}2. 工具列表请求tools/list
{"jsonrpc":"2.0","id":2,"method":"tools/list"}3. 工具调用请求tools/call
{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"calculate","arguments":{"expression":"2+3*4"}}}4. 响应格式
{"jsonrpc":"2.0","id":3,"result":{"content":[{"type":"text","text":"计算结果：14"}]}}MCP服务器实现要点
1. 必需的方法
initialize：服务器初始化tools/list：返回可用工具列表tools/call：执行具体的工具调用
2. 工具定义结构
{"name":"工具名称","description":"工具描述","inputSchema":{"type":"object","properties":{"参数名":{"type":"参数类型","description":"参数描述"}},"required":["必需参数列表"]}}3. 错误处理
{"jsonrpc":"2.0","id":请求ID,"error":{"code":错误代码,"message":"错误描述"}}MCP服务器例子
#!/usr/bin/env python3 #-*-coding:utf-8-*-""" 简单的MCP服务器示例 提供基本的计算工具"""importjsonimportsysfromtypingimportDict,Any,List,OptionalclassSimpleMCPServer:"""简单的MCP服务器实现"""def__init__(self):self.tools={"calculate":{"name":"calculate","description":"执行简单的数学计算","inputSchema":{"type":"object","properties":{"expression":{"type":"string","description":"要计算的数学表达式，如 '2+3*4'"}},"required":["expression"]}},}defhandle_request(self,request:Dict[str,Any])->Dict[str,Any]:"""处理MCP请求"""method=request.get("method")ifmethod=="initialize":returnself._handle_initialize(request)elif method=="tools/list":returnself._handle_tools_list(request)elif method=="tools/call":returnself._handle_tools_call(request)else:return{"jsonrpc":"2.0","id":self._get_request_id(request),"error":{"code":-32601,"message":f"未知方法: {method}"}}def_handle_initialize(self,request:Dict[str,Any])->Dict[str,Any]:"""处理初始化请求"""return{"jsonrpc":"2.0","id":self._get_request_id(request),"result":{"protocolVersion":"2024-11-05","capabilities":{"tools":{}},"serverInfo":{"name":"SimpleMCPServer","version":"1.0.0"}}}def_handle_tools_list(self,request:Dict[str,Any])->Dict[str,Any]:"""处理工具列表请求"""return{"jsonrpc":"2.0","id":self._get_request_id(request),"result":{"tools":list(self.tools.values())}}def_handle_tools_call(self,request:Dict[str,Any])->Dict[str,Any]:"""处理工具调用请求"""params=request.get("params",{})tool_name=params.get("name")arguments=params.get("arguments",{})try:iftool_name=="calculate":result=self._calculate(arguments.get("expression",""))else:return{"jsonrpc":"2.0","id":self._get_request_id(request),"error":{"code":-32601,"message":f"未知工具: {tool_name}"}}return{"jsonrpc":"2.0","id":self._get_request_id(request),"result":{"content":[{"type":"text","text":json.dumps(result,ensure_ascii=False,indent=2)}]}}except Exceptionase:return{"jsonrpc":"2.0","id":self._get_request_id(request),"error":{"code":-32603,"message":f"工具执行错误: {str(e)}"}}def_calculate(self,expression:str)->Dict[str,Any]:"""执行数学计算"""try:# 安全的数学表达式计算 allowed_chars=set("0123456789+-*/.() ")ifnotall(cinallowed_charsforcinexpression):raiseValueError("表达式包含不允许的字符")result=eval(expression)return{"expression":expression,"result":result,"type":"number"}except Exceptionase:raiseValueError(f"计算错误: {str(e)}")def_get_request_id(self,request:Dict[str,Any])->Any:"""获取请求ID，如果请求中没有ID则返回默认ID"""if"id"inrequest:returnrequest["id"]else:# 如果请求中没有id，返回一个默认的字符串IDreturn"default-id"defrun(self):"""运行MCP服务器"""print("Simple MCP Server 启动中...",file=sys.stderr)try:forlineinsys.stdin:line=line.strip()ifnot line:continuetry:request=json.loads(line)response=self.handle_request(request)print(json.dumps(response,ensure_ascii=True))sys.stdout.flush()except json.JSONDecodeError:error_response={"jsonrpc":"2.0","id":"default-id","error":{"code":-32700,"message":"解析错误"}}print(json.dumps(error_response,ensure_ascii=False))sys.stdout.flush()except KeyboardInterrupt:print("服务器关闭",file=sys.stderr)if__name__=="__main__":server=SimpleMCPServer()server.run()简单计算器MCP服务器
本项目中的simple_mcp_server.py是一个完整的MCP服务器示例，包含：
- 数学计算工具：执行基本数学表达式
- 文本统计工具：分析文本的字符、单词等统计信息
- 系统信息工具：获取Python和系统基本信息
可以通过以下方式测试：
# 启动服务器python simple_mcp_server.py# 在另一个终端测试echo'{"jsonrpc":"2.0","id":1,"method":"tools/list"}'|python simple_mcp_server.py真实cursor上加配置调用即可
{“mcpServers”:{“my-server”:{“command”:“python”,“args”:[“D:/sase-dfx/sase_dfx/9、ai生成/simple_mcp_server.py”],“disabled”:false,“alwaysAllow”:[“calculate”]}}}
)
