diff --git a/src/google/adk/tools/base_toolset.py b/src/google/adk/tools/base_toolset.py
index 0e3d8070..6bd1384e 100644
--- a/src/google/adk/tools/base_toolset.py
+++ b/src/google/adk/tools/base_toolset.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
 
 from abc import ABC
 from abc import abstractmethod