fix(mcp): Initialize tool_name_prefix in MCPToolse #2823

shsha4 · 2025-09-02T13:26:14Z

Description
This change introduces a tool_name_prefix attribute to McpToolset and McpToolsetConfig. This allows for adding a prefix to the
names of all tools within the toolset, which can help avoid naming collisions and provide better organization.

The implementation involves updating the McpToolset's init and from_config methods to handle the new tool_name_prefix and
adding the corresponding field to McpToolsetConfig.

Testing Plan
A new unit test file has been added to ensure the functionality works as expected.

tests/unittests/tools/test_mcp_toolset.py:
- The test_mcp_toolset_with_prefix test case verifies that the tool_name_prefix is correctly applied to the tool names
  retrieved from the toolset.
- All tests were run via pytest and passed.

Related Issue

Closes MCPToolset doesn't support inherited tool_name_prefix parameter from BaseToolset #2814

google-cla · 2025-09-02T13:26:18Z

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gemini-code-assist

Summary of Changes

Hello @shsha4, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the McpToolset by adding a tool_name_prefix attribute. This allows users to specify a prefix for all tools managed by a McpToolset instance, which is crucial for avoiding naming conflicts and maintaining better organization, especially in complex environments where multiple toolsets might be in use. The change involves modifications to the McpToolset class and its configuration, along with the addition of dedicated unit tests to ensure functionality.

Highlights

New Feature: Tool Name Prefixing: Introduced a tool_name_prefix attribute to McpToolset and McpToolsetConfig to allow adding a configurable prefix to tool names within a toolset. This helps in preventing naming collisions and improving organization.
Configuration Integration: The tool_name_prefix can now be configured via McpToolsetConfig and is properly handled during McpToolset initialization and when loading configurations.
Enhanced Test Coverage: A new unit test file (tests/unittests/tools/test_mcp_toolset.py) has been added, including test_mcp_toolset_with_prefix, to validate the correct application of the tool name prefixing functionality.

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adk-bot · 2025-09-02T13:27:22Z

Response from ADK Triaging Agent

Hello @shsha4, thank you for creating this PR!

It looks like you haven't signed the Contributor License Agreement (CLA) yet. Please make sure to sign it, as we can't accept contributions without it. You can find more information in the "checks" section of this pull request.

Thanks!

gemini-code-assist

Code Review

This pull request correctly introduces the tool_name_prefix functionality to McpToolset and McpToolsetConfig, allowing for better organization and avoidance of tool name collisions. The changes are consistently applied, and a new unit test is added to verify the feature. My review includes one suggestion to improve the robustness of the new test to more accurately reflect its intent.

gemini-code-assist · 2025-09-02T13:27:42Z

tests/unittests/tools/test_mcp_toolset.py

+  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"


This test correctly verifies that get_tools_with_prefix() returns prefixed tools. However, the assertion that 'the original tools are not modified' isn't being tested as robustly as it could be. Because McpToolset.get_tools() creates new tool instances on each call, the test doesn't guarantee non-mutation if get_tools() were to be changed to cache instances in the future. The suggested change ensures get_tools_with_prefix() operates on the same tool instances that are later checked for mutation, making the test more robust.

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 original tools first to serve as the ground truth original_tools = await toolset.get_tools() # Mock get_tools to return the same instances, to test for mutation. toolset.get_tools = AsyncMock(return_value=original_tools) # 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" # Ensure they are new objects (copies) assert prefixed_tools[0] is not original_tools[0] assert prefixed_tools[1] is not original_tools[1] # Assert that the original tool instances were not modified assert original_tools[0].name == "tool1" assert original_tools[1].name == "tool2"

alberto-mate · 2025-09-02T14:59:54Z

When applying this pull request, a "Tool not found" error will occur if the MCP does not have the prefix. For improved agent behavior, the prefix should be included to resolve naming conflicts in the declaration. However, when making a request to the MCP, the agent should use the tool's name without the prefix.

Check this PR as example

#1226

alberto-mate · 2025-09-04T10:02:37Z

Hi, the only change that this PR needs to be merged is the following:

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

Line 134 in 0dce65c

response = await session.call_tool(self.name, arguments=args)

response = await session.call_tool(self._mcp_tool.name, arguments=args)

alberto-mate · 2025-09-05T08:18:55Z

Hi @shsha4, can you apply the changes that I suggested above and push them into this PR? I don't have the permissions to do so :)

shsha4 · 2025-09-05T09:10:18Z

@alberto-mate
Apologies for the delayed response - I was caught up with work and just had a chance to review this. Please take a look when you have time.

alberto-mate · 2025-09-05T10:31:13Z

Thanks for the contribution!

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

shsha4 · 2025-09-06T02:51:17Z

@seanzhou1023
Hi , I have made the requested changes

seanzhou1023 · 2025-09-08T19:54:56Z

please fix the test failure. follow other mcp test to skip mcp tests when python version is less than 3.10

- Change self.name to self._mcp_tool.name in call_tool invocation - Ensures MCP server receives unprefixed tool name - Addresses review comment from alberto-mate

- Change tool_name_prefix default from empty string to None - Update type annotation to Optional[str] in both McpToolset and McpToolsetConfig - Addresses review comment from seanzhou1023

- Add Python version check to test_mcp_toolset.py - Follow existing MCP test pattern with pytestmark skipif decorator - Add import error handling with dummy classes for test collection - Addresses review comment from seanzhou1023

shsha4 · 2025-09-10T23:57:37Z

@seanzhou1023
Hello, I have made the requested changes. Please review them.

gemini-code-assist bot reviewed Sep 2, 2025

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adk-bot added bot triaged [Bot] This issue is triaged by ADK bot mcp [Component] Issues about MCP support labels Sep 2, 2025

adk-bot requested a review from seanzhou1023 September 2, 2025 13:27

gemini-code-assist bot reviewed Sep 2, 2025

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shsha4 force-pushed the fix/issue-2814 branch from 5e21bc2 to 1cd9ff4 Compare September 5, 2025 11:14

seanzhou1023 reviewed Sep 5, 2025

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src/google/adk/tools/mcp_tool/mcp_toolset.py Outdated Show resolved Hide resolved

seanzhou1023 reviewed Sep 5, 2025

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seanzhou1023 approved these changes Sep 8, 2025

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seanzhou1023 self-assigned this Sep 8, 2025

shsha4 force-pushed the fix/issue-2814 branch 3 times, most recently from c987331 to a33b54a Compare September 10, 2025 13:28

shsha4 added 4 commits September 11, 2025 08:56

fix(mcp): Initialize tool_name_prefix in MCPToolse

c845f56

fix(mcp): Use original tool name when calling MCP server

11bd20b

- Change self.name to self._mcp_tool.name in call_tool invocation - Ensures MCP server receives unprefixed tool name - Addresses review comment from alberto-mate

fix(mcp): Make tool_name_prefix parameter optional in McpToolset

a30d190

- Change tool_name_prefix default from empty string to None - Update type annotation to Optional[str] in both McpToolset and McpToolsetConfig - Addresses review comment from seanzhou1023

shsha4 force-pushed the fix/issue-2814 branch from a33b54a to 76e1122 Compare September 10, 2025 23:56

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