diff --git a/tiramisu/config.py b/tiramisu/config.py
index efa2ba5..332a9f1 100644
--- a/tiramisu/config.py
+++ b/tiramisu/config.py
@@ -223,7 +223,14 @@ class Config(object):
         return self._getattr(name)
 
     def _getattr(self, name, permissive=False):
-        "attribute notation mechanism for accessing the value of an option"
+        """
+        attribute notation mechanism for accessing the value of an option
+        :param name: attribute name
+        :param permissive: permissive doesn't raise some property error
+        (see ``_cfgimpl_permissive``)
+        :return: option's value if name is an option name, OptionDescription
+        otherwise
+        """
         # attribute access by passing a path,
         # for instance getattr(self, "creole.general.family.adresse_ip_eth0")
         if '.' in name:
diff --git a/tiramisu/option.py b/tiramisu/option.py
index 2d1d7cc..da0b49e 100644
--- a/tiramisu/option.py
+++ b/tiramisu/option.py
@@ -221,6 +221,14 @@ class Option(HiddenBaseType, DisabledBaseType):
         return config._cfgimpl_value_owners[self._name]
 
     def is_default_owner(self, config, all_default=True):
+        """
+        :param config: *must* be only the **parent** config
+        (not the toplevel config)
+        :param all_default: only for multi options, if True and the owner list
+        has something else than "default" returns False, if False and the owner
+        list has at least one "default" owner, returns True
+        :return: boolean
+        """
         if self.is_multi():
             owners = self.getowner(config)
             for owner in owners: