Agent Development Kit(ADK)

An easy-to-use and powerful framework to build AI agents.

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

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+# 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 typing import Optional
+
+from google.genai.types import FunctionDeclaration
+from typing_extensions import override
+
+# Attempt to import MCP Tool from the MCP library, and hints user to upgrade
+# their Python version to 3.10 if it fails.
+try:
+  from mcp import ClientSession
+  from mcp.types import Tool as McpBaseTool
+except ImportError as e:
+  import sys
+
+  if sys.version_info < (3, 10):
+    raise ImportError(
+        "MCP Tool requires Python 3.10 or above. Please upgrade your Python"
+        " version."
+    ) from e
+  else:
+    raise e
+
+from ..base_tool import BaseTool
+from ...auth.auth_credential import AuthCredential
+from ...auth.auth_schemes import AuthScheme
+from ..openapi_tool.openapi_spec_parser.rest_api_tool import to_gemini_schema
+from ..tool_context import ToolContext
+
+
+class MCPTool(BaseTool):
+  """Turns a MCP Tool into a Vertex Agent Framework Tool.
+
+  Internally, the tool initializes from a MCP Tool, and uses the MCP Session to
+  call the tool.
+  """
+
+  def __init__(
+      self,
+      mcp_tool: McpBaseTool,
+      mcp_session: ClientSession,
+      auth_scheme: Optional[AuthScheme] = None,
+      auth_credential: Optional[AuthCredential] | None = None,
+  ):
+    """Initializes a MCPTool.
+
+    This tool wraps a MCP Tool interface and an active MCP Session. It invokes
+    the MCP Tool through executing the tool from remote MCP Session.
+
+    Example:
+        tool = MCPTool(mcp_tool=mcp_tool, mcp_session=mcp_session)
+
+    Args:
+        mcp_tool: The MCP tool to wrap.
+        mcp_session: The MCP session to use to call the tool.
+        auth_scheme: The authentication scheme to use.
+        auth_credential: The authentication credential to use.
+
+    Raises:
+        ValueError: If mcp_tool or mcp_session is None.
+    """
+    if mcp_tool is None:
+      raise ValueError("mcp_tool cannot be None")
+    if mcp_session is None:
+      raise ValueError("mcp_session cannot be None")
+    self.name = mcp_tool.name
+    self.description = mcp_tool.description if mcp_tool.description else ""
+    self.mcp_tool = mcp_tool
+    self.mcp_session = mcp_session
+    # TODO(cheliu): Support passing auth to MCP Server.
+    self.auth_scheme = auth_scheme
+    self.auth_credential = auth_credential
+
+  @override
+  def _get_declaration(self) -> FunctionDeclaration:
+    """Gets the function declaration for the tool.
+
+    Returns:
+        FunctionDeclaration: The Gemini function declaration for the tool.
+    """
+    schema_dict = self.mcp_tool.inputSchema
+    parameters = to_gemini_schema(schema_dict)
+    function_decl = FunctionDeclaration(
+        name=self.name, description=self.description, parameters=parameters
+    )
+    return function_decl
+
+  @override
+  async def run_async(self, *, args, tool_context: ToolContext):
+    """Runs the tool asynchronously.
+
+    Args:
+        args: The arguments as a dict to pass to the tool.
+        tool_context: The tool context from upper level ADK agent.
+
+    Returns:
+        Any: The response from the tool.
+    """
+    # TODO(cheliu): Support passing tool context to MCP Server.
+    response = await self.mcp_session.call_tool(self.name, arguments=args)
+    return response