diff --git a/doc/source/api/csst_proto.rst b/doc/source/api/csst_proto.rst
index 1e73d515718df0d7b566c82bbe8a814a7688f16c..cdfced7bf2b224830748a1fa3c6d0063270c4767 100644
--- a/doc/source/api/csst_proto.rst
+++ b/doc/source/api/csst_proto.rst
@@ -2,6 +2,7 @@ API
 ===
 
 .. automodule:: csst_proto.top_level_interface
+   :noindex:
    :members:
    :undoc-members:
    :show-inheritance:
diff --git a/doc/source/codestyle.rst b/doc/source/codestyle.rst
index b57903f708fbfe76ca2957107472f646ab40ca42..2a1326b8751a3cddf2428c9295114d876a5a50ae 100644
--- a/doc/source/codestyle.rst
+++ b/doc/source/codestyle.rst
@@ -39,9 +39,23 @@ Files/directories with asterisks (*) marks are optional.
 Code Style
 ==========
 Python code should follow PEP 8
-    - https://peps.python.org/pep-0008/
+
+- https://peps.python.org/pep-0008/
+
 Whereas C/C++ code should follow PEP 7
-    - https://peps.python.org/pep-0007/
+
+- https://peps.python.org/pep-0007/
+
+Many IDEs (Pycharm, etc) and tools can be used to validate code style
+
+- pycodestyle:
+    - https://pycodestyle.pycqa.org/en/latest/
+
+In our case, we recommend the following method to check code style
+
+.. code-block:: bash
+
+    pycodestyle ./**/*.py --ignore=E121,E123,E126,E226,E24,E704,W503,W504,E501,E722
 
 
 Numpy-style docstring
@@ -50,9 +64,24 @@ There are several popular docstring styles, namely Google, reStructuredText, and
 The CSST DAS adopts Numpydoc-style among the three.
 We refer our developers to the Numpydoc official style guide for instructions on
 how to write docstrings.
-    - https://numpydoc.readthedocs.io/en/latest/format.html
+
+- https://numpydoc.readthedocs.io/en/latest/format.html
+
 In particular, a complete example is available here.
-    - https://numpydoc.readthedocs.io/en/latest/example.html
+
+- https://numpydoc.readthedocs.io/en/latest/example.html
+
+In our case, we recommend the following method to check docstring
+
+.. code-block:: bash
+
+    python -m numpydoc --validate {YOUR_PACKAGE}.top_level_interface.{YOUR_FUNCTION/CLASS}
+
+For example,
+
+.. code-block:: bash
+
+    python -m numpydoc --validate csst_proto.top_level_interface.flip_image
 
 
 Markup language