diff --git a/src/google/adk/tools/mcp_tool/mcp_tool.py b/src/google/adk/tools/mcp_tool/mcp_tool.py
index 773637d1d6..f6034fd90b 100644
--- a/src/google/adk/tools/mcp_tool/mcp_tool.py
+++ b/src/google/adk/tools/mcp_tool/mcp_tool.py
@@ -58,6 +58,7 @@
 # part of the ADK public API; consumers flip the env var, not the symbol.
 from .._gemini_schema_util import _to_gemini_schema
 from ..base_authenticated_tool import BaseAuthenticatedTool
+from ..set_model_response_tool import SET_MODEL_RESPONSE_FUNCTION_NAME
 from ..tool_context import ToolContext
 from ..transfer_to_agent_tool import transfer_to_agent
 from .mcp_session_manager import _http_debug_var
@@ -78,6 +79,7 @@
     REQUEST_EUC_FUNCTION_CALL_NAME,
     REQUEST_CONFIRMATION_FUNCTION_CALL_NAME,
     REQUEST_INPUT_FUNCTION_CALL_NAME,
+    SET_MODEL_RESPONSE_FUNCTION_NAME,
     transfer_to_agent.__name__,
 })
 
diff --git a/src/google/adk/tools/set_model_response_tool.py b/src/google/adk/tools/set_model_response_tool.py
index c03392935c..6bdefebd65 100644
--- a/src/google/adk/tools/set_model_response_tool.py
+++ b/src/google/adk/tools/set_model_response_tool.py
@@ -39,6 +39,10 @@
 from .base_tool import BaseTool
 from .tool_context import ToolContext
 
+# Name of the function call the framework injects when `output_schema` is set
+# alongside other tools. Shared with the MCP reserved-name guard.
+SET_MODEL_RESPONSE_FUNCTION_NAME = 'set_model_response'
+
 
 def _merge_json_schema_descriptions(
     target: dict[str, Any], source: dict[str, Any]
@@ -215,7 +219,7 @@ def set_model_response() -> str:
     self.func = set_model_response
 
     super().__init__(
-        name=self.func.__name__,
+        name=SET_MODEL_RESPONSE_FUNCTION_NAME,
         description=self.func.__doc__.strip() if self.func.__doc__ else '',
     )
 
diff --git a/tests/unittests/tools/mcp_tool/test_mcp_tool.py b/tests/unittests/tools/mcp_tool/test_mcp_tool.py
index e67e371d2f..885e805f49 100644
--- a/tests/unittests/tools/mcp_tool/test_mcp_tool.py
+++ b/tests/unittests/tools/mcp_tool/test_mcp_tool.py
@@ -729,6 +729,7 @@ def test_init_with_empty_description(self):
           "adk_request_credential",
           "adk_request_confirmation",
           "adk_request_input",
+          "set_model_response",
           "transfer_to_agent",
       ],
   )
diff --git a/tests/unittests/tools/mcp_tool/test_mcp_toolset.py b/tests/unittests/tools/mcp_tool/test_mcp_toolset.py
index 4dbfdf6c68..2149ef36ae 100644
--- a/tests/unittests/tools/mcp_tool/test_mcp_toolset.py
+++ b/tests/unittests/tools/mcp_tool/test_mcp_toolset.py
@@ -409,6 +409,7 @@ async def test_get_tools_skips_reserved_names(self):
         MockMCPTool("adk_request_credential"),
         MockMCPTool("adk_request_confirmation"),
         MockMCPTool("adk_request_input"),
+        MockMCPTool("set_model_response"),
     ]
     self.mock_session.list_tools = AsyncMock(
         return_value=MockListToolsResult(mock_tools)