diff --git a/packages/toolbox-adk/src/toolbox_adk/tool.py b/packages/toolbox-adk/src/toolbox_adk/tool.py
index 720407bfe..8283496a9 100644
--- a/packages/toolbox-adk/src/toolbox_adk/tool.py
+++ b/packages/toolbox-adk/src/toolbox_adk/tool.py
@@ -266,17 +266,14 @@ async def run_async(
                         "error": f"OAuth2 Credentials required for {self.name}. A consent link has been generated for the user. Do NOT attempt to run this tool again until the user confirms they have logged in."
                     }
 
-        result: Optional[Any] = None
-        error: Optional[Exception] = None
-
         try:
             # Execute the core tool
-            result = await self._core_tool(**args)
-            return result
-
+            return await self._core_tool(**args)
         except Exception as e:
-            error = e
-            raise e
+            logging.warning(
+                "Toolbox tool '%s' execution failed: %s", self.name, e, exc_info=True
+            )
+            return {"error": f"{type(e).__name__}: {e}", "is_error": True}
         finally:
             if reset_token:
                 USER_TOKEN_CONTEXT_VAR.reset(reset_token)
diff --git a/packages/toolbox-adk/tests/unit/test_tool.py b/packages/toolbox-adk/tests/unit/test_tool.py
index 0f3c5120d..1bd262ceb 100644
--- a/packages/toolbox-adk/tests/unit/test_tool.py
+++ b/packages/toolbox-adk/tests/unit/test_tool.py
@@ -56,6 +56,21 @@ async def test_auth_check_no_token(self):
         # Should proceed to execute (auth not forced)
         mock_core.assert_awaited()
 
+    @pytest.mark.asyncio
+    async def test_run_async_returns_error_on_exception(self):
+        mock_core = AsyncMock(side_effect=RuntimeError("boom"))
+        mock_core.__name__ = "my_tool"
+        mock_core.__doc__ = "my description"
+
+        tool = ToolboxTool(mock_core)
+        ctx = MagicMock()
+
+        result = await tool.run_async({"arg": 1}, ctx)
+
+        assert isinstance(result, dict) and "error" in result
+        assert result.get("is_error") is True
+        assert "RuntimeError" in result["error"]
+
     @pytest.mark.asyncio
     async def test_bind_params(self):
         mock_core = MagicMock()