diff --git a/swh/scheduler/celery_backend/pika_listener.py b/swh/scheduler/celery_backend/pika_listener.py
--- a/swh/scheduler/celery_backend/pika_listener.py
+++ b/swh/scheduler/celery_backend/pika_listener.py
@@ -1,8 +1,13 @@
-# Copyright (C) 2020  The Software Heritage developers
+# Copyright (C) 2020-2021  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+"""This module is the scheduler listener. It listens to rabbitmq events and flushes the
+oneshot tasks' status in the scheduler backend.
+
+"""
+
 import json
 import logging
 import sys
diff --git a/swh/scheduler/celery_backend/runner.py b/swh/scheduler/celery_backend/runner.py
--- a/swh/scheduler/celery_backend/runner.py
+++ b/swh/scheduler/celery_backend/runner.py
@@ -3,6 +3,14 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+"""Module in charge of defining the first scheduler runner. It's scheduling oneshot
+tasks (save code now, indexer, vault, deposit).
+
+It's working with the scheduler listener
+:mod:`swh.scheduler.celery_backend.pika_listener`.
+
+"""
+
 import logging
 from typing import Dict, List, Tuple