refactor: enhance module documentation and improve function descriptions across the codebase

gemini_key_manager/exceptions.py

@@ -1,9 +1,18 @@
-"""
-Custom exceptions for the Gemini Key Management script.
+"""Exception hierarchy for Gemini Key Management system.
+
+Defines domain-specific exceptions for:
+- Terms of Service compliance failures
+- Permission-related errors
+- API operation constraints
 """
 
 class TermsOfServiceNotAcceptedError(Exception):
-    """Raised when the Terms of Service for a required API have not been accepted."""
+    """Indicates unaccepted Terms of Service for critical API operations.
+    
+    Attributes:
+        message (str): Human-readable error description
+        url (str): URL for Terms of Service acceptance portal
+    """
     def __init__(self, message, url):
         self.message = message
         self.url = url