diff --git a/src/primaite/acl/__init__.py b/src/primaite/acl/__init__.py
index 63f825c2..434e5899 100644
--- a/src/primaite/acl/__init__.py
+++ b/src/primaite/acl/__init__.py
@@ -1 +1,2 @@
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
+"""Access Control List. Models firewall functionality."""
\ No newline at end of file
diff --git a/src/primaite/agents/__init__.py b/src/primaite/agents/__init__.py
index e69de29b..90d719b4 100644
--- a/src/primaite/agents/__init__.py
+++ b/src/primaite/agents/__init__.py
@@ -0,0 +1 @@
+"""Common interface between RL agents from different libraries and PrimAITE."""
\ No newline at end of file
diff --git a/src/primaite/common/__init__.py b/src/primaite/common/__init__.py
index 63f825c2..e79054cf 100644
--- a/src/primaite/common/__init__.py
+++ b/src/primaite/common/__init__.py
@@ -1 +1,2 @@
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
+"""Objects which are shared between many PrimAITE modules."""
\ No newline at end of file
diff --git a/src/primaite/data_viz/__init__.py b/src/primaite/data_viz/__init__.py
index a7cc3e8b..ca28900e 100644
--- a/src/primaite/data_viz/__init__.py
+++ b/src/primaite/data_viz/__init__.py
@@ -1,5 +1,5 @@
 from enum import Enum
-
+"""Utility to generate plots of sessions metrics after PrimAITE."""
 
 class PlotlyTemplate(Enum):
     """The built-in plotly templates."""
diff --git a/src/primaite/environment/__init__.py b/src/primaite/environment/__init__.py
index 63f825c2..6f82aec1 100644
--- a/src/primaite/environment/__init__.py
+++ b/src/primaite/environment/__init__.py
@@ -1 +1,2 @@
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
+"""Gym/Gymnasium environment for RL agents consisting of a simulated computer network."""
\ No newline at end of file
diff --git a/src/primaite/links/__init__.py b/src/primaite/links/__init__.py
index 63f825c2..919c35ac 100644
--- a/src/primaite/links/__init__.py
+++ b/src/primaite/links/__init__.py
@@ -1 +1,2 @@
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
+"""Network connections between nodes in the simulation."""
\ No newline at end of file
diff --git a/src/primaite/nodes/__init__.py b/src/primaite/nodes/__init__.py
index 63f825c2..5db9f9b5 100644
--- a/src/primaite/nodes/__init__.py
+++ b/src/primaite/nodes/__init__.py
@@ -1 +1,2 @@
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
+"""Nodes represent network hosts in the simulation."""
\ No newline at end of file
diff --git a/src/primaite/notebooks/__init__.py b/src/primaite/notebooks/__init__.py
index 0730312e..da65da38 100644
--- a/src/primaite/notebooks/__init__.py
+++ b/src/primaite/notebooks/__init__.py
@@ -1,3 +1,4 @@
+"""Contains default jupyter notebooks which demonstrate PrimAITE functionality."""
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
 import importlib.util
 import os
diff --git a/src/primaite/pol/__init__.py b/src/primaite/pol/__init__.py
index 63f825c2..cba4b28b 100644
--- a/src/primaite/pol/__init__.py
+++ b/src/primaite/pol/__init__.py
@@ -1 +1,2 @@
+"""Pattern of Life- Represents the actions of users on the network."""
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
diff --git a/src/primaite/primaite_session.py b/src/primaite/primaite_session.py
index ed2b9bf1..4aa8476a 100644
--- a/src/primaite/primaite_session.py
+++ b/src/primaite/primaite_session.py
@@ -1,3 +1,4 @@
+"""Main entry point to PrimAITE. Configure training/evaluation experiments and input/output."""
 from __future__ import annotations
 
 from pathlib import Path
@@ -35,12 +36,12 @@ class PrimaiteSession:
         """
         if not isinstance(training_config_path, Path):
             training_config_path = Path(training_config_path)
-        self._training_config_path: Final[Union[Path]] = training_config_path
+        self._training_config_path: Final[Union[Path, str]] = training_config_path
         self._training_config: Final[TrainingConfig] = training_config.load(self._training_config_path)
 
         if not isinstance(lay_down_config_path, Path):
             lay_down_config_path = Path(lay_down_config_path)
-        self._lay_down_config_path: Final[Union[Path]] = lay_down_config_path
+        self._lay_down_config_path: Final[Union[Path, str]] = lay_down_config_path
         self._lay_down_config: Dict = lay_down_config.load(self._lay_down_config_path)
 
         self._agent_session: AgentSessionABC = None  # noqa
diff --git a/src/primaite/setup/__init__.py b/src/primaite/setup/__init__.py
index 63f825c2..3c0bfe14 100644
--- a/src/primaite/setup/__init__.py
+++ b/src/primaite/setup/__init__.py
@@ -1 +1,2 @@
+"""Utilities to prepare the user's data folders."""
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
diff --git a/src/primaite/transactions/__init__.py b/src/primaite/transactions/__init__.py
index 63f825c2..45315b22 100644
--- a/src/primaite/transactions/__init__.py
+++ b/src/primaite/transactions/__init__.py
@@ -1 +1,2 @@
+"""Record data of the system's state and agent's observations and actions."""
 # Crown Copyright (C) Dstl 2022. DEFCON 703. Shared in confidence.
diff --git a/src/primaite/utils/__init__.py b/src/primaite/utils/__init__.py
index e69de29b..878f1d75 100644
--- a/src/primaite/utils/__init__.py
+++ b/src/primaite/utils/__init__.py
@@ -0,0 +1 @@
+"""Utilities for PrimAITE."""
\ No newline at end of file