I have read about meta descriptions here on the webmasters forum. Is it necessary or important to have description on pages that are not being index by the search engine? Like for instances, pages in "Members Area" section of my site or pages blocked by a robots.txt file.
If the pages will not be available to search engines, and your site has no use for them internally, then you can safely omit them.
If pages are not for indexing in search engines, then you can do anything with these pages, it will not affect to your ranking of other website pages, but must do not forget about the user experience of these pages, as these pages will not be interacted by search engines, but they will be interacted by users.