Is the "description" field used, other than on Twitter posts? I'm always confused myself as what to write there, usually choosing some odd cross between the title and first sentence.
I don't think it's bad that people should be expected to have the first paragraphc function as an abstract/preview. That's fairly common across the web, and many services rely on it.
It's used in these boxes
Either way, the proposed feature would show enough of the article preview that if it didn't give an idea of what the post was all about, the author is being waayyyyy too clever.
I'm always for iterative evolution. Text only at first (if the content is embed-only, tell the reader that) and add more stuff in the coming iterations.
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