diff --git a/src/power_grid_model_io_native/__init__.py b/src/power_grid_model_io_native/__init__.py
index 7359a3b..b42cd18 100644
--- a/src/power_grid_model_io_native/__init__.py
+++ b/src/power_grid_model_io_native/__init__.py
@@ -2,4 +2,6 @@
 #
 # SPDX-License-Identifier: MPL-2.0
 
+"""Module importing PowerGridModelIoCore."""
+
 from power_grid_model_io_native._core.power_grid_model_io_core import PowerGridModelIoCore
diff --git a/src/power_grid_model_io_native/_core/power_grid_model_io_core.py b/src/power_grid_model_io_native/_core/power_grid_model_io_core.py
index 75388cc..749f381 100644
--- a/src/power_grid_model_io_native/_core/power_grid_model_io_core.py
+++ b/src/power_grid_model_io_native/_core/power_grid_model_io_core.py
@@ -11,6 +11,8 @@
 
 from power_grid_model.core.power_grid_core import IdxC, CStr, CharPtr
 
+"""PGM IO CORE module."""
+
 # functions with size_t return
 _FUNC_SIZE_T_RES = {"meta_class_size", "meta_class_alignment", "meta_attribute_offset"}
 _ARGS_TYPE_MAPPING = {bytes: CharPtr, str: CStr, int: IdxC, float: c_double}