Issue with `ib_insync` and asyncio event loop in `fastmcp` environment

[rossdem699]

Description

Hello,

I am experiencing an issue when trying to use the ib_insync library within a fastmcp tool. I am consistently getting a "This event loop is already running" error when I try to connect to Interactive Brokers using ib_insync.

I have spent a significant amount of time trying to debug this issue, and I have tried numerous workarounds, including:

• Using both synchronous and asynchronous versions of the ib_insync connection code.
• Using ib_insync.util.run() to manage the event loop.
• Using ib_insync.util.startLoop() which is designed for environments with a running event loop.
• Using nest_asyncio.apply() to patch the asyncio event loop.
• Using different clientIds for each connection attempt to avoid conflicts.
• Analyzing multiple existing IBKR MCP server implementations on GitHub to find a working solution.
• Refactoring the code to use a professional-grade client from a known-working implementation.

Unfortunately, none of these approaches have solved the problem. The "event loop is already running" error persists in all cases.

This leads me to believe that there is a fundamental incompatibility between the fastmcp environment's asyncio event loop and the ib_insync library. It seems that ib_insync is unable to
integrate with the event loop that is already running in the fastmcp tool's environment.

I would be grateful if you could look into this issue. It seems that it is not possible to use ib_insync within a fastmcp tool at the moment.

Thank you for your time and consideration. FYI - i have been using gemini_cli to try and troubleshoot this issue and it has given up on me!!!

Example Code

1. `stock_tool.py`

  This file defines the get_account_details tool that is being called in the fastmcp environment.

    1 from fastmcp import FastMCP
    2 from ibkr_service import ibkr_service
    3
    4 mcp = FastMCP(name="Stock and IBKR Tool")
    5
    6 @mcp.tool()
    7 async def get_account_details(account: str = None) -> list:
    8     """
    9     Connects to IBKR TWS and retrieves account summary details.
   10     An optional account code can be provided to filter for a specific account.
   11     """
   12     try:
   13         # The ibkr_service is already a singleton, so we can just call its methods
   14         details = await ibkr_service.fetch_portfolio_details()
   15         # The user wants the account summary, so we extract it from the details
   16         return details.get('account_summary', [])
   17     except Exception as e:
   18         return [{"error": f"An error occurred: {e}"}]

 2. `ibkr_service.py`

  This file contains the logic for connecting to Interactive Brokers and demonstrates the use of nest_asyncio.

    1 import os
    2 from typing import List, Dict
    3 from fastapi import HTTPException
    4 from ib_async import IB
    5 from dotenv import load_dotenv
    6 import asyncio
    7 import nest_asyncio
    8 try:
    9     nest_asyncio.apply()
   10 except ValueError as e:
   11     print(f"nest_asyncio.apply() skipped: {e}")
   12
   13 load_dotenv(override=True)
   14
   15 class IBKRService:
   16     def __init__(self):
   17         self.ib = IB()
   18         self.host = os.getenv("IBKR_HOST", "127.0.0.1")
   19         raw_port = os.getenv("IBKR_PORT", "7496").split()[0]
   20         self.port = int(raw_port)
   21         self.connected = False
   22
   23     async def connect(self):
   24         """Connect to IBKR TWS or Gateway"""
   25         if self.connected:
   26             return
   27
   28         try:
   29             print(f"Connecting to IBKR at {self.host}:{self.port}")
   30             await self.ib.connectAsync(
   31                 host=self.host,
   32                 port=self.port,
   33                 clientId=0,
   34                 readonly=True,
   35                 timeout=20
   36             )
   37             self.connected = True
   38             print(f"Connected to IBKR at {self.host}:{self.port}")
   39         except Exception as e:
   40             self.connected = False
   41             raise HTTPException(status_code=500, detail=f"Failed to connect to IBKR: {str(e)}")
   42
   43     def disconnect(self):
   44         """Disconnect from IBKR"""
   45         if self.connected:
   46             self.ib.disconnect()
   47             self.connected = False
   48             print("Disconnected from IBKR")
   49
   50     async def fetch_portfolio_details(self) -> Dict:
   51         """Fetch portfolio details from IBKR"""
   52         try:
   53             if not self.connected:
   54                 await self.connect()
   55
   56             print("=>>>>>> Fetching portfolio details")
   57             # Get portfolio positions
   58             positions = await asyncio.to_thread(self.ib.positions)
   59             print("=>>>>>> Positions fetched: ", positions)
   60
   61             # Format portfolio data
   62             portfolio_data = []
   63             for pos in positions:
   64                 position_data = {
   65                     'symbol': pos.contract.symbol,
   66                     'secType': pos.contract.secType,
   67                     'exchange': pos.contract.exchange,
   68                     'currency': pos.contract.currency,
   69                     'position': pos.position,
   70                     'avgCost': pos.avgCost
   71                 }
   72                 portfolio_data.append(position_data)
   73
   74             print("=>>>>>> Portfolio data: ", portfolio_data)
   75             # Get account summary
   76             print("=>>>>>> Fetching account summary")
   77             account = await self.ib.accountSummaryAsync()
   78
   79             return {
   80                 'positions': portfolio_data,
   81                 'account_summary': account
   82             }
   83
   84         except Exception as e:
   85             raise HTTPException(
   86                 status_code=500,
   87                 detail=f"Failed to fetch portfolio: {str(e)}"
   88             )
   89         finally:
   90             self.disconnect()
   91
   92 # Create a singleton instance
   93 ibkr_service = IBKRService()

  Explanation to Include

  When you submit the issue, you can explain that:
   * The get_account_details tool in stock_tool.py is called from the fastmcp environment.
   * This tool then calls the fetch_portfolio_details method in ibkr_service.py.
   * The ibkr_service.py file uses nest_asyncio.apply() in an attempt to solve the event loop issue, but the error still occurs.

Version Information

✦ Here are the versions you requested:

   * Python Version: 3.13.5
   * `fastmcp` Version: 2.12.0
   * `ib_insync` Version: 0.9.86

[marvin-context-protocol]

Found 1 possible duplicate issue:

1. Incompatibility with nest_asyncio #1080: Incompatibility with nest_asyncio

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

Additional context:
This issue appears to be a manifestation of a known incompatibility between fastmcp's event loop management (based on anyio) and libraries that use nest_asyncio. The maintainer has previously indicated that this is a fundamental architectural limitation, making it challenging to use ib_insync within the fastmcp environment.

[jlowin]

FastMCP uses asyncio.run to start an event loop only when you call your server’s run() method. If you need control of the event loop or are starting it in another place (which seems to be the case here), you could call the server’s run_async method instead to get a coroutine and manage its execution yourself.

I love the utility of nest asyncio but note that it is no longer maintained and the MCP SDK is built on anyio, not asyncio, so it may not work as expected!