diff --git a/src/google/adk/tools/discovery_engine_search_tool.py b/src/google/adk/tools/discovery_engine_search_tool.py
index 11bc37c7ed..e9ad4abda1 100644
--- a/src/google/adk/tools/discovery_engine_search_tool.py
+++ b/src/google/adk/tools/discovery_engine_search_tool.py
@@ -14,6 +14,7 @@
 
 from __future__ import annotations
 
+import re
 from typing import Any
 from typing import Optional
 
@@ -25,6 +26,9 @@
 
 from .function_tool import FunctionTool
 
+_LOCATION_PATTERN = re.compile(r"/locations/([^/]+)/")
+_DEFAULT_ENDPOINT = "discoveryengine.googleapis.com"
+
 
 class DiscoveryEngineSearchTool(FunctionTool):
   """Tool for searching the discovery engine."""
@@ -74,10 +78,19 @@ def __init__(
 
     credentials, _ = google.auth.default()
     quota_project_id = getattr(credentials, "quota_project_id", None)
-    options = (
-        client_options.ClientOptions(quota_project_id=quota_project_id)
-        if quota_project_id
-        else None
+
+    resource_id = data_store_id or search_engine_id or ""
+    location_match = _LOCATION_PATTERN.search(resource_id)
+    location = location_match.group(1) if location_match else "global"
+    api_endpoint = (
+        f"{location}-{_DEFAULT_ENDPOINT}"
+        if location != "global"
+        else _DEFAULT_ENDPOINT
+    )
+
+    options = client_options.ClientOptions(
+        api_endpoint=api_endpoint,
+        quota_project_id=quota_project_id,
     )
     self._discovery_engine_client = discoveryengine.SearchServiceClient(
         credentials=credentials, client_options=options
diff --git a/tests/unittests/tools/test_discovery_engine_search_tool.py b/tests/unittests/tools/test_discovery_engine_search_tool.py
index 7cba5f1841..a6be520f2f 100644
--- a/tests/unittests/tools/test_discovery_engine_search_tool.py
+++ b/tests/unittests/tools/test_discovery_engine_search_tool.py
@@ -121,7 +121,8 @@ def test_discovery_engine_search_success(
       assert result["results"][0]["content"] == "Test Content"
       mock_auth.assert_called_once()
       mock_client_options.ClientOptions.assert_called_once_with(
-          quota_project_id="test-quota-project"
+          api_endpoint="discoveryengine.googleapis.com",
+          quota_project_id="test-quota-project",
       )
       mock_search_client.assert_called_once_with(
           credentials=mock_credentials,
@@ -156,3 +157,71 @@ def test_discovery_engine_search_no_results(self, mock_search_client):
 
     assert result["status"] == "success"
     assert not result["results"]
+
+  @mock.patch.object(discovery_engine_search_tool, "client_options")
+  @mock.patch.object(discoveryengine, "SearchServiceClient")
+  def test_regional_endpoint_eu_data_store(
+      self, mock_search_client, mock_client_options
+  ):
+    """Test that an EU data store uses the EU regional endpoint."""
+    DiscoveryEngineSearchTool(
+        data_store_id="projects/my-project/locations/eu/collections/default_collection/dataStores/my-ds"
+    )
+    mock_client_options.ClientOptions.assert_called_once_with(
+        api_endpoint="eu-discoveryengine.googleapis.com",
+        quota_project_id=None,
+    )
+
+  @mock.patch.object(discovery_engine_search_tool, "client_options")
+  @mock.patch.object(discoveryengine, "SearchServiceClient")
+  def test_regional_endpoint_us_search_engine(
+      self, mock_search_client, mock_client_options
+  ):
+    """Test that a US search engine uses the US regional endpoint."""
+    DiscoveryEngineSearchTool(
+        search_engine_id="projects/my-project/locations/us/collections/default_collection/engines/my-engine"
+    )
+    mock_client_options.ClientOptions.assert_called_once_with(
+        api_endpoint="us-discoveryengine.googleapis.com",
+        quota_project_id=None,
+    )
+
+  @mock.patch.object(discovery_engine_search_tool, "client_options")
+  @mock.patch.object(discoveryengine, "SearchServiceClient")
+  def test_regional_endpoint_single_region(
+      self, mock_search_client, mock_client_options
+  ):
+    """Test that a single-region location uses the correct endpoint."""
+    DiscoveryEngineSearchTool(
+        data_store_id="projects/my-project/locations/europe-west1/collections/default_collection/dataStores/my-ds"
+    )
+    mock_client_options.ClientOptions.assert_called_once_with(
+        api_endpoint="europe-west1-discoveryengine.googleapis.com",
+        quota_project_id=None,
+    )
+
+  @mock.patch.object(discovery_engine_search_tool, "client_options")
+  @mock.patch.object(discoveryengine, "SearchServiceClient")
+  def test_global_endpoint_explicit(
+      self, mock_search_client, mock_client_options
+  ):
+    """Test that a global data store uses the default global endpoint."""
+    DiscoveryEngineSearchTool(
+        data_store_id="projects/my-project/locations/global/collections/default_collection/dataStores/my-ds"
+    )
+    mock_client_options.ClientOptions.assert_called_once_with(
+        api_endpoint="discoveryengine.googleapis.com",
+        quota_project_id=None,
+    )
+
+  @mock.patch.object(discovery_engine_search_tool, "client_options")
+  @mock.patch.object(discoveryengine, "SearchServiceClient")
+  def test_global_endpoint_no_location_in_id(
+      self, mock_search_client, mock_client_options
+  ):
+    """Test that a short ID without location falls back to global endpoint."""
+    DiscoveryEngineSearchTool(data_store_id="test_data_store")
+    mock_client_options.ClientOptions.assert_called_once_with(
+        api_endpoint="discoveryengine.googleapis.com",
+        quota_project_id=None,
+    )