diff --git a/langchain/vectorstores/mongodb_atlas.py b/langchain/vectorstores/mongodb_atlas.py
index d2ef0b1b9b..98e21563ad 100644
--- a/langchain/vectorstores/mongodb_atlas.py
+++ b/langchain/vectorstores/mongodb_atlas.py
@@ -69,6 +69,7 @@ class MongoDBAtlasVectorSearch(VectorStore):
                 document.
             embedding_key: MongoDB field that will contain the embedding for
                 each document.
+            index_name: Name of the Atlas Search index.
         """
         self._collection = collection
         self._embedding = embedding