chore: Deprecate ApiRegistry in favor of AgentRegistry

Adds deprecation warnings and updates docstrings for ApiRegistry and
google.adk.integrations.api_registry, directing users to use AgentRegistry
(google.adk.integrations.agent_registry) instead.

Co-authored-by: Kathy Wu <wukathy@google.com>
PiperOrigin-RevId: 956174446

src/google/adk/integrations/api_registry/__init__.py

@@ -12,8 +12,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import warnings
+
 from .api_registry import ApiRegistry
 
+warnings.warn(
+    "google.adk.integrations.api_registry is deprecated, use"
+    " google.adk.integrations.agent_registry instead.",
+    DeprecationWarning,
+    stacklevel=2,
+)
+
 __all__ = [
-    'ApiRegistry',
+    "ApiRegistry",
 ]

src/google/adk/integrations/api_registry/api_registry.py

@@ -17,6 +17,7 @@ from __future__ import annotations
 import os
 from typing import Any
 from typing import Callable
+import warnings
 
 from google.adk.agents.readonly_context import ReadonlyContext
 from google.adk.tools.base_toolset import ToolPredicate
@@ -50,7 +51,11 @@ def _get_api_registry_url(client_cert_source: Any | None = None) -> str:
 
 
 class ApiRegistry:
-  """Registry that provides McpToolsets for MCP servers registered in API Registry."""
+  """[DEPRECATED] Registry for MCP servers registered in API Registry.
+
+  Deprecated: Use AgentRegistry from `google.adk.integrations.agent_registry`
+  instead.
+  """
 
   def __init__(
       self,
@@ -68,6 +73,12 @@ class ApiRegistry:
       header_provider: Optional function to provide additional headers for MCP
         server calls.
     """
+    warnings.warn(
+        "ApiRegistry is deprecated. Use AgentRegistry from"
+        " google.adk.integrations.agent_registry instead.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
     self.api_registry_project_id = api_registry_project_id
     self.location = location
     self._credentials, _ = google.auth.default()

src/google/adk/tools/api_registry.py

@@ -19,8 +19,8 @@ import warnings
 from google.adk.integrations.api_registry import ApiRegistry as ApiRegistry
 
 warnings.warn(
-    "google.adk.tools.api_registry is moved to"
-    " google.adk.integrations.api_registry",
+    "google.adk.tools.api_registry is deprecated, use"
+    " google.adk.integrations.agent_registry instead.",
     DeprecationWarning,
     stacklevel=2,
 )

tests/unittests/integrations/api_registry/test_api_registry.py

@@ -81,6 +81,18 @@ class TestApiRegistry(unittest.IsolatedAsyncioTestCase):
     mock_use_cert_patcher.start()
     self.addCleanup(mock_use_cert_patcher.stop)
 
+  def test_deprecation_warning(self):
+    mock_response = MagicMock()
+    mock_response.raise_for_status = MagicMock()
+    mock_response.json = MagicMock(return_value=MOCK_MCP_SERVERS_LIST)
+    self.mock_session.get.return_value = mock_response
+
+    with self.assertWarns(DeprecationWarning) as cm:
+      ApiRegistry(
+          api_registry_project_id=self.project_id, location=self.location
+      )
+    self.assertIn("ApiRegistry is deprecated", str(cm.warning))
+
   def test_init_success(self):
     mock_response = MagicMock()
     mock_response.raise_for_status = MagicMock()