diff --git a/api/core/workflow/utils/variable_utils.py b/api/core/workflow/utils/variable_utils.py
index e68d990b60..868868315b 100644
--- a/api/core/workflow/utils/variable_utils.py
+++ b/api/core/workflow/utils/variable_utils.py
@@ -7,6 +7,7 @@ def append_variables_recursively(
 ):
     """
     Append variables recursively
+    :param pool: variable pool to append variables to
     :param node_id: node id
     :param variable_key_list: variable key list
     :param variable_value: variable value