It wouldn't really be in full paragraph/sentence format, because that would be way too difficult. Instead, the would-be writer picks a few parameters - number of characters, whether the characters are all male, all female, or a mix, and the genre.** It then spits out character descriptions and backstory elements, a setting, theme, and plot coupons using the created characters. Naturally there would be a good mix of cracktastic elements.
So... I think I need to maybe come up with some samples of what the output would look like, because I'll be able to work out how to produce them then.
* Or horrific drug side-effects or something.
** Shounen, shoujo, josei, seinen, yaoi, yuri, BL, shoujo-ai.*** Josei, seinen, yaoi, and yuri would pick settings and plot coupons from options that involve more adult themes - harems, offices, career worries, horror, etc. I'd want to keep this PG-13.
*** I have an evil desire to add "hentai" and have the entire result for that option be: "What plot?"