tools/call hangs on Windows while direct handler returns successfully

[MaheshSurepalli]

Summary

On Windows, analytics-mcp starts successfully over stdio and responds to initialize and tools/list, but tools/call never returns for get_account_summaries and eventually times out in the MCP client.

The Google Analytics credentials and API access are valid: calling the same package's underlying handler directly returns the expected account/property data in a few seconds.

Environment

• OS: Windows 11 ARM64
• Python used for pipx cache: 3.12.6
• analytics-mcp: 0.4.0
• mcp: 1.27.1
• google-adk: 1.33.0
• starlette: 0.52.1
• Launch command follows the README:

{
  "command": "pipx",
  "args": ["run", "analytics-mcp"],
  "env": {
    "GOOGLE_APPLICATION_CREDENTIALS": "<path-to-application_default_credentials.json>",
    "GOOGLE_PROJECT_ID": "<project-id>"
  }
}

I also set PIPX_DEFAULT_PYTHON to a Python 3.12 interpreter to avoid a separate Python 3.14 pipx install issue.

Reproduction

Using an MCP client against the official stdio server:

1. Start server with pipx run analytics-mcp.
2. Send initialize.
3. Send notifications/initialized.
4. Send tools/list.
5. Send tools/call for get_account_summaries with {}.

Observed:

• initialize returns successfully.
• tools/list returns 8 tools.
• tools/call for get_account_summaries times out after 60-120 seconds.

Expected

tools/call should return the same account summaries that the underlying handler returns directly.

Direct handler succeeds

Running this directly inside the same pipx cache returns successfully in about 6-7 seconds:

import asyncio
from analytics_mcp import coordinator

async def main():
    result = await asyncio.wait_for(
        coordinator.call_mcp_tool("get_account_summaries", {}),
        timeout=30,
    )
    print(result[0].text)

asyncio.run(main())

The underlying Google Analytics Admin API also returns successfully with the same ADC credentials.

Additional checks

• Cleared stale pipx run caches and rebuilt fresh.
• Verified fresh cache contains analytics-mcp 0.4.0.
• Tested mcp==1.24.0 because analytics-mcp declares mcp>=1.24.0; the tools/call timeout still occurred, so reverted to mcp 1.27.1.
• analytics-mcp 0.4.0 correctly writes the startup message to stderr, not stdout.
• Raw stdio JSON-RPC shows initialize and tools/list responses, but no response for tools/call before timeout.

Notes

This does not appear to be an auth/scope issue. The same ADC file can call Google Analytics Admin REST and the direct Python handler successfully.

[matt-landers]

We'll be pushing a 0.6.0 release this week which should address this issue. #154

[matt-landers]

This should be resolved with v0.6.0