这几天我在写sse-mcp-server时发现，tool如果是同步执行，执行时间大约10秒客户端就会报超时异常MCP error -32001: Maximum total timeout exceeded，我把官方文档和所有issue、discussions全看了一遍，

目前针对长任务有两种情况：
1.执行时间不超过client端的Maximum Total Timeout(比如60s)，则可以report_progress来保持连接。否则10秒就抛异常，但是如果超过Maximum Total Timeout，使用report_progress也一样没用。
2.执行时间超过client端的Maximum Total Timeout，大概只能异步执行，然后另行通知处理。

设置client端超时时间过长也不是个通用好办法，可能引来更多问题

下面是一个mcp server使用ctx.report_progress的demo，本地可以使用npx -y @modelcontextprotocol/inspector来测试效果

#!/usr/bin/env python3
import asyncio
import logging
from datetime import datetime
from typing import Any, Dict
from mcp.server.fastmcp import FastMCP, Context
from mcp.server.sse import SseServerTransport
from starlette.applications import Starlette
from starlette.requests import Request
from starlette.routing import Mount, Route
from starlette.responses import PlainTextResponse
import uvicorn

# 简单日志配置
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(message)s')
logger = logging.getLogger("mcp")

# 创建FastMCP服务器 (24小时超时)
mcp = FastMCP("progress-test-server", server_options={"timeout": 86400})

# 全局进度追踪
current_progress = 0
start_time = None

@mcp.tool()
async def progress_test(iterations: int = 100000, sleep_time: float = 0.1, ctx: Context = None) -> Dict[str, Any]:
    """持续调用report_progress测试最长支持时间"""
    global current_progress, start_time
    start_time = datetime.now()
    current_progress = 0
    
    if not ctx:
        return {"error": "无上下文对象"}
    
    try:
        for i in range(iterations):
            current_progress = i + 1
            
            # 仅在关键节点记录日志，减少噪音
            if current_progress % 100 == 0:
                elapsed = (datetime.now() - start_time).total_seconds()
                logger.info(f"进度: {current_progress}/{iterations} - 已运行: {elapsed:.1f}秒")
            
            # 持续报告进度
            await ctx.report_progress(float(current_progress), float(iterations))
            await asyncio.sleep(sleep_time)
    
    except Exception as e:
        return {"error": str(e), "iterations_completed": current_progress}
    
    total_time = (datetime.now() - start_time).total_seconds()
    return {"completed": current_progress, "seconds": total_time}

# 创建服务器应用
def create_app():
    sse = SseServerTransport("/messages/")
    
    async def handle_sse(request: Request):
        try:
            async with sse.connect_sse(request.scope, request.receive, request._send) as (r, w):
                await mcp._mcp_server.run(r, w, mcp._mcp_server.create_initialization_options())
                return PlainTextResponse("Connection closed")
        except Exception as e:
            return PlainTextResponse(f"Error: {str(e)}", status_code=500)
    
    return Starlette(
        routes=[
            Route("/sse", endpoint=handle_sse),
            Mount("/messages/", app=sse.handle_post_message),
        ],
    )

if __name__ == "__main__":
    print("\n===== 进度报告测试服务器 =====")
    print("端点: http://localhost:8000/sse")
    print("客户端: npx -y @modelcontextprotocol/inspector http://localhost:8000/sse --timeout 86400000")
    uvicorn.run(create_app(), host="localhost", port=8000)