Replies that read like a person who was already in the thread
The fastest way to get downvoted is to write three paragraphs where everyone else wrote two lines. You give PostGuard a sentence about what you actually want to say, and three replies come back at the median length of that thread, in its register. In communities that ban AI content, it stops entirely.
Length matched to the thread
The median comment length in the thread sets the target, and your short, medium or long choice scales against it. Long, structured, hedged answers are the single clearest tell of a generated reply, so the drafts avoid the shape as well as the vocabulary.
Your point, not the model's
The note you write is the message, and the model is told to choose wording only. It must not add an experience, a number, a tool or a product that your note did not mention, because you are the one whose account posts it.
You edit, you post
Each draft comes with a copy button and nothing else. Nothing is typed into the page and nothing is ever submitted for you. In communities whose rules ban AI-written content, the drafting panel does not appear at all.