diff --git a/backend/tracim_backend/models/context_models.py b/backend/tracim_backend/models/context_models.py
index 8720ae6c..297bd389 100644
--- a/backend/tracim_backend/models/context_models.py
+++ b/backend/tracim_backend/models/context_models.py
@@ -730,7 +730,7 @@ def frontend_url(self) -> str:
     @property
     def page_nb(self) -> typing.Optional[int]:
         """
-        :return: page_nb of content if available
+        :return: page_nb of content if available, None if unavailable
         """
         if self.content.depot_file:
             from tracim_backend.lib.core.content import ContentApi
@@ -746,14 +746,14 @@ def page_nb(self) -> typing.Optional[int]:
     @property
     def mimetype(self) -> str:
         """
-        :return: mimetype of content if available
+        :return: mimetype of content if available, None if unavailable
         """
         return self.content.file_mimetype
 
     @property
     def size(self) -> typing.Optional[int]:
         """
-        :return: size of content if available
+        :return: size of content if available, None if unavailable
         """
         if self.content.depot_file:
             return self.content.depot_file.file.content_length
@@ -918,7 +918,7 @@ def slug(self) -> str:
     @property
     def page_nb(self) -> typing.Optional[int]:
         """
-        :return: page_nb of content if available
+        :return: page_nb of content if available, None if unavailable
         """
         if self.revision.depot_file:
             # TODO - G.M - 2018-09-05 - Fix circular import better
@@ -935,14 +935,14 @@ def page_nb(self) -> typing.Optional[int]:
     @property
     def mimetype(self) -> str:
         """
-        :return: mimetype of content if available
+        :return: mimetype of content if available, None if unavailable
         """
         return self.revision.file_mimetype
 
     @property
     def size(self) -> typing.Optional[int]:
         """
-        :return: size of content if available
+        :return: size of content if available, None if unavailable
         """
         if self.revision.depot_file:
             return self.revision.depot_file.file.content_length
diff --git a/backend/tracim_backend/views/core_api/schemas.py b/backend/tracim_backend/views/core_api/schemas.py
index 2f762815..ee176f52 100644
--- a/backend/tracim_backend/views/core_api/schemas.py
+++ b/backend/tracim_backend/views/core_api/schemas.py
@@ -831,7 +831,7 @@ class FileInfoAbstractSchema(marshmallow.Schema):
         description='raw text or html description of the file'
     )
     page_nb = marshmallow.fields.Int(
-        description='number of pages',
+        description='number of pages, return null value if unaivalable',
         example=1,
         allow_none=True,
     )
@@ -841,7 +841,7 @@ class FileInfoAbstractSchema(marshmallow.Schema):
         required=True,
     )
     size = marshmallow.fields.Int(
-        description='file size in byte',
+        description='file size in byte, return null value if unaivalable',
         example=1024,
         allow_none=True,
     )