fix: resolve Windows stdio deadlocks caused by grpc.aio and google.auth

analytics_mcp/tools/admin/info.py

@@ -14,27 +14,33 @@
 
 """Tools for gathering Google Analytics account and property information."""
 
+import asyncio
+import sys
 from typing import Any, Dict, List
 
 from analytics_mcp.tools.utils import (
     construct_property_rn,
     create_admin_api_client,
+    create_admin_api_client_sync,
     create_admin_alpha_api_client,
+    create_admin_alpha_api_client_sync,
     proto_to_dict,
 )
 from google.analytics import admin_v1beta, admin_v1alpha
 
 
 async def get_account_summaries() -> List[Dict[str, Any]]:
     """Retrieves information about the user's Google Analytics accounts and properties."""
+    if sys.platform == "win32":
+        def _fetch():
+            client = create_admin_api_client_sync()
+            summary_pager = client.list_account_summaries()
+            return [proto_to_dict(summary_page) for summary_page in summary_pager]
+        return await asyncio.to_thread(_fetch)
 
-    # Uses an async list comprehension so the pager returned by
-    # list_account_summaries retrieves all pages.
-    summary_pager = await create_admin_api_client().list_account_summaries()
-    all_pages = [
-        proto_to_dict(summary_page) async for summary_page in summary_pager
-    ]
-    return all_pages
+    client = create_admin_api_client()
+    summary_pager = await client.list_account_summaries()
+    return [proto_to_dict(summary_page) for summary_page in summary_pager]
 
 
 async def list_google_ads_links(property_id: int | str) -> List[Dict[str, Any]]:
@@ -48,13 +54,19 @@ async def list_google_ads_links(property_id: int | str) -> List[Dict[str, Any]]:
     request = admin_v1beta.ListGoogleAdsLinksRequest(
         parent=construct_property_rn(property_id)
     )
-    # Uses an async list comprehension so the pager returned by
-    # list_google_ads_links retrieves all pages.
+
+    if sys.platform == "win32":
+        def _fetch():
+            links_pager = create_admin_api_client_sync().list_google_ads_links(
+                request=request
+            )
+            return [proto_to_dict(link_page) for link_page in links_pager]
+        return await asyncio.to_thread(_fetch)
+
     links_pager = await create_admin_api_client().list_google_ads_links(
         request=request
     )
-    all_pages = [proto_to_dict(link_page) async for link_page in links_pager]
-    return all_pages
+    return [proto_to_dict(link_page) for link_page in links_pager]
 
 
 async def get_property_details(property_id: int | str) -> Dict[str, Any]:
@@ -64,10 +76,18 @@ async def get_property_details(property_id: int | str) -> Dict[str, Any]:
           - A number
           - A string consisting of 'properties/' followed by a number
     """
-    client = create_admin_api_client()
     request = admin_v1beta.GetPropertyRequest(
         name=construct_property_rn(property_id)
     )
+
+    if sys.platform == "win32":
+        def _fetch():
+            client = create_admin_api_client_sync()
+            response = client.get_property(request=request)
+            return proto_to_dict(response)
+        return await asyncio.to_thread(_fetch)
+
+    client = create_admin_api_client()
     response = await client.get_property(request=request)
     return proto_to_dict(response)
 
@@ -89,13 +109,16 @@ async def list_property_annotations(
     request = admin_v1alpha.ListReportingDataAnnotationsRequest(
         parent=construct_property_rn(property_id)
     )
-    annotations_pager = (
-        await create_admin_alpha_api_client().list_reporting_data_annotations(
-            request=request
-        )
+
+    if sys.platform == "win32":
+        def _fetch():
+            annotations_pager = create_admin_alpha_api_client_sync().list_reporting_data_annotations(
+                request=request
+            )
+            return [proto_to_dict(annotation_page) for annotation_page in annotations_pager]
+        return await asyncio.to_thread(_fetch)
+
+    annotations_pager = await create_admin_alpha_api_client().list_reporting_data_annotations(
+        request=request
     )
-    all_pages = [
-        proto_to_dict(annotation_page)
-        async for annotation_page in annotations_pager
-    ]
-    return all_pages
+    return [proto_to_dict(annotation_page) for annotation_page in annotations_pager]

analytics_mcp/tools/reporting/core.py

@@ -14,6 +14,8 @@
 
 """Tools for running core reports using the Data API."""
 
+import asyncio
+import sys
 from typing import Any, Dict, List
 
 from analytics_mcp.tools.reporting.metadata import (
@@ -25,6 +27,7 @@
 from analytics_mcp.tools.utils import (
     construct_property_rn,
     create_data_api_client,
+    create_data_api_client_sync,
     proto_to_dict,
 )
 from google.analytics import data_v1beta
@@ -167,6 +170,12 @@ async def run_report(
     if currency_code:
         request.currency_code = currency_code
 
-    response = await create_data_api_client().run_report(request)
+    if sys.platform == "win32":
+        def _fetch():
+            return proto_to_dict(
+                create_data_api_client_sync().run_report(request)
+            )
+        return await asyncio.to_thread(_fetch)
 
+    response = await create_data_api_client().run_report(request)
     return proto_to_dict(response)

analytics_mcp/tools/reporting/metadata.py

@@ -14,11 +14,14 @@
 
 """Metadata to provide context and hints for reporting tools."""
 
+import asyncio
+import sys
 from typing import Any, Dict, List
 
 from analytics_mcp.tools.utils import (
     construct_property_rn,
     create_data_api_client,
+    create_data_api_client_sync,
     proto_to_dict,
     proto_to_json,
 )
@@ -319,6 +322,27 @@ async def get_custom_dimensions_and_metrics(
           - A string consisting of 'properties/' followed by a number
 
     """
+    if sys.platform == "win32":
+        def _fetch():
+            metadata = create_data_api_client_sync().get_metadata(
+                name=f"{construct_property_rn(property_id)}/metadata"
+            )
+            custom_metrics = [
+                proto_to_dict(metric)
+                for metric in metadata.metrics
+                if metric.custom_definition
+            ]
+            custom_dimensions = [
+                proto_to_dict(dimension)
+                for dimension in metadata.dimensions
+                if dimension.custom_definition
+            ]
+            return {
+                "custom_dimensions": custom_dimensions,
+                "custom_metrics": custom_metrics,
+            }
+        return await asyncio.to_thread(_fetch)
+
     metadata = await create_data_api_client().get_metadata(
         name=f"{construct_property_rn(property_id)}/metadata"
     )

analytics_mcp/tools/reporting/realtime.py

@@ -14,11 +14,14 @@
 
 """Tools for running realtime reports using the Data API."""
 
+import asyncio
+import sys
 from typing import Any, Dict, List
 
 from analytics_mcp.tools.utils import (
     construct_property_rn,
     create_data_api_client,
+    create_data_api_client_sync,
     proto_to_dict,
 )
 from analytics_mcp.tools.reporting.metadata import (
@@ -157,5 +160,12 @@ async def run_realtime_report(
     if offset:
         request.offset = offset
 
+    if sys.platform == "win32":
+        def _fetch():
+            return proto_to_dict(
+                create_data_api_client_sync().run_realtime_report(request)
+            )
+        return await asyncio.to_thread(_fetch)
+
     response = await create_data_api_client().run_realtime_report(request)
     return proto_to_dict(response)

analytics_mcp/tools/utils.py

@@ -14,12 +14,15 @@
 
 """Common utilities used by the MCP server."""
 
+import os
+import sys
 from typing import Any, Dict
 
 from google.analytics import admin_v1beta, data_v1beta, admin_v1alpha
 from google.api_core.gapic_v1.client_info import ClientInfo
 from importlib import metadata
 import google.auth
+import google.oauth2.credentials
 import proto
 
 
@@ -46,11 +49,58 @@ def _get_package_version_with_fallback():
 
 
 def _create_credentials() -> google.auth.credentials.Credentials:
-    """Returns Application Default Credentials with read-only scope."""
+    """Returns Application Default Credentials with read-only scope.
+
+    On Windows, prefers loading credentials directly from the file specified
+    by GOOGLE_APPLICATION_CREDENTIALS to avoid subprocess spawning, which can
+    interfere with the MCP server's stdio transport.
+    """
+    if sys.platform == "win32":
+        path = os.environ.get("GOOGLE_APPLICATION_CREDENTIALS")
+        if path and os.path.exists(path):
+            return google.oauth2.credentials.Credentials.from_authorized_user_file(
+                path, scopes=[_READ_ONLY_ANALYTICS_SCOPE]
+            )
     credentials, _ = google.auth.default(scopes=[_READ_ONLY_ANALYTICS_SCOPE])
     return credentials
 
 
+def create_admin_api_client_sync() -> admin_v1beta.AnalyticsAdminServiceClient:
+    """Returns a properly configured Google Analytics Admin API sync client.
+
+    Uses Application Default Credentials with read-only scope.
+    On Windows, this sync client is used instead of the async variant to
+    avoid grpc.aio event loop conflicts with the MCP stdio transport.
+    """
+    return admin_v1beta.AnalyticsAdminServiceClient(
+        client_info=_CLIENT_INFO, credentials=_create_credentials()
+    )
+
+
+def create_data_api_client_sync() -> data_v1beta.BetaAnalyticsDataClient:
+    """Returns a properly configured Google Analytics Data API sync client.
+
+    Uses Application Default Credentials with read-only scope.
+    On Windows, this sync client is used instead of the async variant to
+    avoid grpc.aio event loop conflicts with the MCP stdio transport.
+    """
+    return data_v1beta.BetaAnalyticsDataClient(
+        client_info=_CLIENT_INFO, credentials=_create_credentials()
+    )
+
+
+def create_admin_alpha_api_client_sync() -> admin_v1alpha.AnalyticsAdminServiceClient:
+    """Returns a properly configured Google Analytics Admin API (alpha) sync client.
+
+    Uses Application Default Credentials with read-only scope.
+    On Windows, this sync client is used instead of the async variant to
+    avoid grpc.aio event loop conflicts with the MCP stdio transport.
+    """
+    return admin_v1alpha.AnalyticsAdminServiceClient(
+        client_info=_CLIENT_INFO, credentials=_create_credentials()
+    )
+
+
 def create_admin_api_client() -> admin_v1beta.AnalyticsAdminServiceAsyncClient:
     """Returns a properly configured Google Analytics Admin API async client.