diff --git a/corrlib/find.py b/corrlib/find.py
index 3cbe09b..cb85130 100644
--- a/corrlib/find.py
+++ b/corrlib/find.py
@@ -66,6 +66,22 @@ def _project_lookup_by_id(db: Path, uuid: str) -> list[tuple[str, ...]]:
 
 
 def _time_filter(results: pd.DataFrame,  created_before: Optional[str]=None, created_after: Optional[Any]=None, updated_before: Optional[Any]=None, updated_after: Optional[Any]=None) -> pd.DataFrame:
+    """
+    Filter the results from the database in terms of the creation and update times.
+
+    Parameters
+    ----------
+    results: pd.DataFrame
+        The dataframe holding the unfilteres results from the database.
+    created_before: str
+        Contraint on the creation date in datetime.datetime.isoformat. Note that this is exclusive. The creation date has to be truly before the date and time given.
+    created_after: str
+        Contraint on the creation date in datetime.datetime.isoformat. Note that this is exclusive. The creation date has to be truly after the date and time given.
+    updated_before: str
+        Contraint on the creation date in datetime.datetime.isoformat. Note that this is exclusive. The date of the last update has to be truly before the date and time given.
+    updated_after: str
+        Contraint on the creation date in datetime.datetime.isoformat. Note that this is exclusive. The date of the last update has to be truly after the date and time given.
+    """
     drops = []
     for ind in range(len(results)):
         result = results.iloc[ind]