diff --git a/model_manager/sientia/reports.py b/model_manager/sientia/reports.py
index 7a12fee..dc66b59 100644
--- a/model_manager/sientia/reports.py
+++ b/model_manager/sientia/reports.py
@@ -55,6 +55,22 @@ def inject_content(main_html, section_id, content):
 
 
 class Reports:
+    """
+    Report generator using Evidently library.
+
+    Thread-safety: This class is NOT thread-safe. Multiple threads should not
+    call add_*_section() methods on the same instance simultaneously as they
+    modify shared state (self.metrics, self.sections, self.options).
+
+    For multi-threaded environments:
+    - Create separate Reports instances per thread
+    - Or synchronize access using locks
+    - After generation, instances are safe for read-only operations
+
+    I/O Note: This class relies on Evidently's report.save_html() method
+    for file operations. Ensure Evidently properly manages file handles.
+    """
+
     def __init__(
         self, reference_data: Any, current_data: Any, base_path: str | None = None
     ) -> None:
@@ -95,6 +111,7 @@ class Reports:
             report.run(reference_data=self.ref_data, current_data=self.cur_data)
             self.sections['data_quality'] = report.as_dict()
             if self.base_path:
+                # Note: Relies on Evidently's save_html() to properly manage file I/O
                 report.save_html(os.path.join(self.base_path, 'data_quality.html'))
 
     def add_data_drift_section(self, columns: list[str] | None = None, run: bool = True) -> None:
@@ -111,6 +128,7 @@ class Reports:
             report.run(reference_data=self.ref_data, current_data=self.cur_data)
             self.sections['data_drift'] = report.as_dict()
             if self.base_path:
+                # Note: Relies on Evidently's save_html() to properly manage file I/O
                 report.save_html(os.path.join(self.base_path, 'data_drift.html'))
 
     def add_regression_section(self, run: bool = True) -> None:
@@ -135,6 +153,7 @@ class Reports:
             report.run(reference_data=self.ref_data, current_data=self.cur_data)
             self.sections['regression'] = report.as_dict()
             if self.base_path:
+                # Note: Relies on Evidently's save_html() to properly manage file I/O
                 report.save_html(os.path.join(self.base_path, 'regression.html'))
 
     def set_color_options(
@@ -201,10 +220,23 @@ class Reports:
 
         Args:
             report_path: The path to save the report HTML file.
+
+        Raises:
+            ValueError: If base_path is not set
+            OSError: If directory creation or file writing fails
+
+        Note:
+            This method uses context manager (with open) to ensure file is properly closed.
+            Creates parent directories if they don't exist.
         """
         if not self.base_path:
             raise ValueError('base_path is required to save all sections HTML')
 
+        # Ensure output directory exists
+        output_dir = os.path.dirname(report_path)
+        if output_dir and not os.path.exists(output_dir):
+            os.makedirs(output_dir, exist_ok=True)
+
         # Load main HTML template
         main_html_path = os.path.join(self.base_path, 'header.html')
         main_html = load_html_from_file(main_html_path)
@@ -222,5 +254,6 @@ class Reports:
         main_html = inject_content(main_html, 'regression', regression_content)
 
         # Save the final HTML to a new file (report.html)
+        # Context manager ensures file is properly closed even if an error occurs
         with open(report_path, 'w', encoding='utf-8') as report_file:
             report_file.write(main_html)