results_size is the total counting of the listing result; and could be easily understood as the sum of size(results) of all pages, while each page contains a maximum of 50 files.
image_url is fixed to be resized to 100x100
description would be returned as a concatenation from blob->meta->search and blob->meta->tags and the parsed list of directories and sub-directories. In case the file doesn't have this field (and is at the root folder), it defaults to No description for this file is available.