In onebox, how to change the description to any paragraph?

Ask: in onebox, how to change the description to any paragraph (how to edit the code in: https://github.com/discourse/onebox ?)

onebox is called when there are: Title, description, photo. (located at: GitHub - discourse/onebox: A gem for turning URLs into website previews)
When we do marketing communications, we know: description describes the title. This makes the content of 1 Onebox not have much other information of the article.
So in onebox, we want change the description to any paragraph of the article. That is, when creating Onebox, instead of using a description, onebox will use any paragraph of the article. (still have tilte, photo).

thanks everyone