diff --git a/libs/langchain/langchain/evaluation/comparison/eval_chain.py b/libs/langchain/langchain/evaluation/comparison/eval_chain.py
index 1a1ba1da67a..e95c72fe5c5 100644
--- a/libs/langchain/langchain/evaluation/comparison/eval_chain.py
+++ b/libs/langchain/langchain/evaluation/comparison/eval_chain.py
@@ -53,7 +53,8 @@ def resolve_pairwise_criteria(
     """Resolve the criteria for the pairwise evaluator.
 
     Args:
-        criteria (Union[CRITERIA_TYPE, str, List[CRITERIA_TYPE]]): The criteria to use.
+        criteria (Union[CRITERIA_TYPE, str, List[CRITERIA_TYPE]], optional):
+        The criteria to use.
 
     Returns:
         dict: The resolved criteria.