diff --git a/tests/unittests/tools/test_enterprise_web_search_tool.py b/tests/unittests/tools/test_enterprise_web_search_tool.py
new file mode 100644
index 000000000..390da4a78
--- /dev/null
+++ b/tests/unittests/tools/test_enterprise_web_search_tool.py
@@ -0,0 +1,98 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from google.adk.agents.invocation_context import InvocationContext
+from google.adk.agents.sequential_agent import SequentialAgent
+from google.adk.models.llm_request import LlmRequest
+from google.adk.sessions.in_memory_session_service import InMemorySessionService
+from google.adk.tools.enterprise_search_tool import EnterpriseWebSearchTool
+from google.adk.tools.tool_context import ToolContext
+from google.genai import types
+import pytest
+
+
+async def _create_tool_context() -> ToolContext:
+  """Creates a ToolContext for testing."""
+  session_service = InMemorySessionService()
+  session = await session_service.create_session(
+      app_name='test_app', user_id='test_user'
+  )
+  agent = SequentialAgent(name='test_agent')
+  invocation_context = InvocationContext(
+      invocation_id='invocation_id',
+      agent=agent,
+      session=session,
+      session_service=session_service,
+  )
+  return ToolContext(invocation_context)
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    'model_name',
+    [
+        'gemini-2.5-flash',
+        'projects/test-project/locations/global/publishers/google/models/gemini-2.5-flash',
+    ],
+)
+async def test_process_llm_request_success_with_gemini_models(model_name):
+  tool = EnterpriseWebSearchTool()
+  llm_request = LlmRequest(
+      model=model_name, config=types.GenerateContentConfig()
+  )
+  tool_context = await _create_tool_context()
+
+  await tool.process_llm_request(
+      tool_context=tool_context, llm_request=llm_request
+  )
+
+  assert (
+      llm_request.config.tools[0].enterprise_web_search
+      == types.EnterpriseWebSearch()
+  )
+
+
+@pytest.mark.asyncio
+async def test_process_llm_request_failure_with_non_gemini_models():
+  tool = EnterpriseWebSearchTool()
+  llm_request = LlmRequest(model='gpt-4o', config=types.GenerateContentConfig())
+  tool_context = await _create_tool_context()
+
+  with pytest.raises(ValueError) as exc_info:
+    await tool.process_llm_request(
+        tool_context=tool_context, llm_request=llm_request
+    )
+  assert 'is not supported for model' in str(exc_info.value)
+
+
+@pytest.mark.asyncio
+async def test_process_llm_request_failure_with_multiple_tools_gemini_1_models():
+  tool = EnterpriseWebSearchTool()
+  llm_request = LlmRequest(
+      model='gemini-1.5-flash',
+      config=types.GenerateContentConfig(
+          tools=[
+              types.Tool(google_search=types.GoogleSearch()),
+          ]
+      ),
+  )
+  tool_context = await _create_tool_context()
+
+  with pytest.raises(ValueError) as exc_info:
+    await tool.process_llm_request(
+        tool_context=tool_context, llm_request=llm_request
+    )
+  assert 'can not be used with other tools in Gemini 1.x.' in str(
+      exc_info.value
+  )