diff --git a/swh/lister/core/indexing_lister.py b/swh/lister/core/indexing_lister.py
--- a/swh/lister/core/indexing_lister.py
+++ b/swh/lister/core/indexing_lister.py
@@ -16,8 +16,6 @@
 
 
 class IndexingLister(ListerBase):
-    flush_packet_db = 20
-    default_min_bound = ''
     """Lister* intermediate class for any service that follows the pattern:
 
     - The service must report at least one stable unique identifier, known
@@ -47,6 +45,14 @@
         def get_next_target_from_response
 
     """
+    flush_packet_db = 20
+    """Number of iterations in-between write flushes of lister repositories to
+       db (see fn:`run`).
+    """
+    default_min_bound = ''
+    """Default initialization value for the minimum boundary index to use when
+       undefined (see fn:`run`).
+    """
 
     @abc.abstractmethod
     def get_next_target_from_response(self, response):