fix(mcp): Initialize tool_name_prefix in MCPToolse

src/google/adk/tools/mcp_tool/mcp_tool.py

@@ -136,7 +136,7 @@ async def _run_async_impl(
     # Get the session from the session manager
     session = await self._mcp_session_manager.create_session(headers=headers)
 
-    response = await session.call_tool(self.name, arguments=args)
+    response = await session.call_tool(self._mcp_tool.name, arguments=args)
     return response
 
   async def _get_headers(

src/google/adk/tools/mcp_tool/mcp_toolset.py

@@ -100,6 +100,7 @@ def __init__(
           StreamableHTTPConnectionParams,
       ],
       tool_filter: Optional[Union[ToolPredicate, List[str]]] = None,
+      tool_name_prefix: Optional[str] = None,
       errlog: TextIO = sys.stderr,
       auth_scheme: Optional[AuthScheme] = None,
       auth_credential: Optional[AuthCredential] = None,
@@ -118,11 +119,13 @@ def __init__(
       tool_filter: Optional filter to select specific tools. Can be either: - A
         list of tool names to include - A ToolPredicate function for custom
         filtering logic
+      tool_name_prefix: A prefix to be added to the name of each tool in this
+        toolset.
       errlog: TextIO stream for error logging.
       auth_scheme: The auth scheme of the tool for tool calling
       auth_credential: The auth credential of the tool for tool calling
     """
-    super().__init__(tool_filter=tool_filter)
+    super().__init__(tool_filter=tool_filter, tool_name_prefix=tool_name_prefix)
 
     if not connection_params:
       raise ValueError("Missing connection params in MCPToolset.")
@@ -207,6 +210,7 @@ def from_config(
     return cls(
         connection_params=connection_params,
         tool_filter=mcp_toolset_config.tool_filter,
+        tool_name_prefix=mcp_toolset_config.tool_name_prefix,
         auth_scheme=mcp_toolset_config.auth_scheme,
         auth_credential=mcp_toolset_config.auth_credential,
     )
@@ -239,6 +243,8 @@ class McpToolsetConfig(BaseToolConfig):
 
   tool_filter: Optional[List[str]] = None
 
+  tool_name_prefix: Optional[str] = None
+
   auth_scheme: Optional[AuthScheme] = None
 
   auth_credential: Optional[AuthCredential] = None

tests/unittests/tools/test_mcp_toolset.py

@@ -0,0 +1,89 @@
+# 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.
+
+"""Unit tests for McpToolset."""
+
+import sys
+from unittest.mock import AsyncMock
+from unittest.mock import MagicMock
+
+import pytest
+
+# Skip all tests in this module if Python version is less than 3.10
+pytestmark = pytest.mark.skipif(
+    sys.version_info < (3, 10), reason="MCP tool requires Python 3.10+"
+)
+
+# Import dependencies with version checking
+try:
+  from google.adk.tools.mcp_tool.mcp_toolset import McpToolset
+except ImportError as e:
+  if sys.version_info < (3, 10):
+    # Create dummy classes to prevent NameError during test collection
+    # Tests will be skipped anyway due to pytestmark
+    class DummyClass:
+      pass
+
+    McpToolset = DummyClass
+  else:
+    raise e
+
+
+@pytest.mark.asyncio
+async def test_mcp_toolset_with_prefix():
+  """Test that McpToolset correctly applies the tool_name_prefix."""
+  # Mock the connection parameters
+  mock_connection_params = MagicMock()
+
+  # Mock the MCPSessionManager and its create_session method
+  mock_session_manager = MagicMock()
+  mock_session = MagicMock()
+
+  # Mock the list_tools response from the MCP server
+  mock_tool1 = MagicMock()
+  mock_tool1.name = "tool1"
+  mock_tool1.description = "tool 1 desc"
+  mock_tool2 = MagicMock()
+  mock_tool2.name = "tool2"
+  mock_tool2.description = "tool 2 desc"
+  list_tools_result = MagicMock()
+  list_tools_result.tools = [mock_tool1, mock_tool2]
+  mock_session.list_tools = AsyncMock(return_value=list_tools_result)
+  mock_session_manager.create_session = AsyncMock(return_value=mock_session)
+
+  # Create an instance of McpToolset with a prefix
+  toolset = McpToolset(
+      connection_params=mock_connection_params,
+      tool_name_prefix="my_prefix",
+  )
+
+  # Replace the internal session manager with our mock
+  toolset._mcp_session_manager = mock_session_manager
+
+  # Get the tools from the toolset
+  tools = await toolset.get_tools()
+
+  # The get_tools method in McpToolset returns MCPTool objects, which are
+  # instances of BaseTool. The prefixing is handled by the BaseToolset,
+  # so we need to call get_tools_with_prefix to get the prefixed tools.
+  prefixed_tools = await toolset.get_tools_with_prefix()
+
+  # Assert that the tools are prefixed correctly
+  assert len(prefixed_tools) == 2
+  assert prefixed_tools[0].name == "my_prefix_tool1"
+  assert prefixed_tools[1].name == "my_prefix_tool2"
+
+  # Assert that the original tools are not modified
+  assert tools[0].name == "tool1"
+  assert tools[1].name == "tool2"