diff --git a/pyproject.toml b/pyproject.toml
index b48b21f..5be6c6e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -45,6 +45,7 @@ dependencies = [
   "sqlalchemy>=2.0",                         # SQL database ORM
   "tzlocal>=5.3",                            # Time zone utilities
   "uvicorn>=0.34.0",                         # ASGI server for FastAPI
+  "toolbox-core>=0.1.0",
   # go/keep-sorted end
 ]
 dynamic = ["version"]
diff --git a/src/google/adk/tools/toolbox_toolset.py b/src/google/adk/tools/toolbox_toolset.py
index 2b2d245..67d3bdb 100644
--- a/src/google/adk/tools/toolbox_toolset.py
+++ b/src/google/adk/tools/toolbox_toolset.py
@@ -12,9 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import List, Optional, override
+from typing import List
+from typing import Optional
 
 import toolbox_core as toolbox
+from typing_extensions import override
 
 from ..agents.readonly_context import ReadonlyContext
 from .base_tool import BaseTool