diff --git a/libs/standard-tests/langchain_standard_tests/unit_tests/chat_models.py b/libs/standard-tests/langchain_standard_tests/unit_tests/chat_models.py
index e55557eaae3..3ffca1bb53b 100644
--- a/libs/standard-tests/langchain_standard_tests/unit_tests/chat_models.py
+++ b/libs/standard-tests/langchain_standard_tests/unit_tests/chat_models.py
@@ -21,6 +21,11 @@ def my_adder_tool(a: int, b: int) -> int:
     return a + b
 
 
+def my_adder(a: int, b: int) -> int:
+    """Takes two integers, a and b, and returns their sum."""
+    return a + b
+
+
 class ChatModelTests(ABC):
     @property
     @abstractmethod
@@ -108,7 +113,7 @@ class ChatModelUnitTests(ChatModelTests):
             return
 
         tool_model = model.bind_tools(
-            [Person, Person.schema(), my_adder_tool], tool_choice="any"
+            [Person, Person.schema(), my_adder_tool, my_adder], tool_choice="any"
         )
         assert isinstance(tool_model, RunnableBinding)