Mediumomatic: %%item_description%% provide a full (not short) content

Hello! I'm trying to get a some nice short description for the posts but cannot understand what %%item_description%% shortcode should provide? In my case it provides a full content, identical to what %%item_content%% . I tried to go deeper to the plugin's code, seems it's not what it supposed to do :) But I cannot understand why it provides full content. I think it should provide some SEO description from Medium's post for example (please see attachment). Also it could be any other sort of short description but not the full content ;) Can you please clarify me this?