diff --git a/src/ghga_connector/core/downloading/downloader.py b/src/ghga_connector/core/downloading/downloader.py
index 1646a4ed..83f3b5bb 100644
--- a/src/ghga_connector/core/downloading/downloader.py
+++ b/src/ghga_connector/core/downloading/downloader.py
@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+"""TODO"""
 
 import base64
 import concurrent.futures
diff --git a/src/ghga_connector/core/downloading/main.py b/src/ghga_connector/core/downloading/main.py
index 86d07d6a..3bcf07cf 100644
--- a/src/ghga_connector/core/downloading/main.py
+++ b/src/ghga_connector/core/downloading/main.py
@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+"""TODO"""
 
 from pathlib import Path
 from queue import Empty, Queue
diff --git a/src/ghga_connector/core/uploading/abstract_uploader.py b/src/ghga_connector/core/uploading/abstract_uploader.py
index 241903be..4f0c8b77 100644
--- a/src/ghga_connector/core/uploading/abstract_uploader.py
+++ b/src/ghga_connector/core/uploading/abstract_uploader.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+"""TODO"""
+
 from abc import ABC, abstractmethod
 from collections.abc import Iterator
 
diff --git a/src/ghga_connector/core/uploading/dataclasses.py b/src/ghga_connector/core/uploading/dataclasses.py
index 41d499ab..d19d3abb 100644
--- a/src/ghga_connector/core/uploading/dataclasses.py
+++ b/src/ghga_connector/core/uploading/dataclasses.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+"""TODO"""
+
 from enum import Enum
 
 
diff --git a/src/ghga_connector/core/uploading/main.py b/src/ghga_connector/core/uploading/main.py
index c8bd1863..d929ea2a 100644
--- a/src/ghga_connector/core/uploading/main.py
+++ b/src/ghga_connector/core/uploading/main.py
@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-
+"""TODO"""
 
 from pathlib import Path