Requesting the mcp server through the mcp stdio method cannot correctly read the environment variables

[Jasper-zh]

Question

Currently, only the second load generated when starting the main process is normal. Each request seems to re-execute the mcp server, and the environment variables cannot be reached.

main process

@app.on_event("startup")
async def startup_event():
    global agent
    agent = await Agent.create()

    process = Popen(
        [sys.executable, "mcp_server/mcp_server_stdio.py"],
        env=os.environ.copy(),
        stdin=PIPE,
        stdout=PIPE,
        stderr=PIPE
    )

mcp server

def get_backend_server():
        return os.getenv("BACKEND_SERVER_URL", "http://192.168.100.25:20484")

@mcp.tool()
def select_bot_event(bot_name=None, status: int=None, sortType: int=None):
    """
    ...
    """

    logging.info(f"backend_server:{get_backend_server()}")

if __name__ == "__main__":
    if "BACKEND_SERVER_URL" in os.environ:
        backend_server = os.environ["BACKEND_SERVER_URL"]
        logger.info(f"env: {backend_server}")
    else:
        logger.warning("NOT FOUND BACKEND_SERVER_URL")
    
    mcp.run(transport="stdio")

logs

2025-07-01 15:58:03,406 - __main__ - WARNING - NOT FOUND BACKEND_SERVER_URL
2025-07-01 15:58:03,419 - mcp.server.lowlevel.server - INFO - Processing request of type ListToolsRequest
2025-07-01 15:58:04,235 - __main__ - INFO - env: http://127.0.0.1:8010
2025-07-01 15:58:30,216 - __main__ - WARNING -  NOT FOUND BACKEND_SERVER_URL2025-07-01 15:58:30,231 - mcp.server.lowlevel.server - INFO - Processing request of type CallToolRequest
2025-07-01 15:58:30,232 - root - INFO - backend_server:http://192.168.100.25:20484

Additional Context

No response

[Jasper-zh]

You can do this by starting the parameter passing method.