In some situations SE software adds a comment which looks like this:1
This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient reputation you will be able to comment on any post.
The comment is signed with some use name. So probably from the comment itself it is not clear whether it was added by some (at least partially) automated process.
However, I am not sure exactly in which situations such comments appear. I decided to ask here rather than experiment, since I do not want to flag some post by mistake. And also low quality posts review queue is empty at the moment, so I cannot experiment there.
I think that knowing exactly when this happens might be useful for some discussions which are currently going on.
Is seems that they can be added when reviewing low quality posts, see: What is the mechanism behind auto-generated "This does not provide an answer to the question" comments? However I am not sure when is it added. Is it only added when I choose "Recommend deletion"? If I choose this option, is there some possibility for me to choose what auto-generated comment is displayed and whether it is displayed at all? (The tag-wiki for the tag automatic-comments on meta.SE says that it is optional.)
Do some flags cause addition of such comment? Namely if I flag some post as "not an answer", is such comment added? Do I have option to decide whether it is added, when I use this type of flag?
Are there some other situations when such comment is added by the software?
Just to clarify, I am asking only when such comments is added by the SE software. Of course, nobody prevents a user from typing such comment manually, add them from some comments repository using some bookmarklet or userscript, or simply copy similar comment from here.
1 I have copied the text of the comment from here. (A deleted post, so it is visible for 10k+ users only.) I cannot know for sure whether it was added by software or actually typed in by a user, but the first possibility seems much more likely, since I found the post from Low quality posts review history.
Until we have some post in the low quality review queue, where we can test the behavior take a screenshot, I will at least add this scree shot shamelessly stolen from this answer on meta.SE. Of course, the options might have changed since then.