Image fourteen tells me nothing
A timestamp is ugly, but at least it answers one question.
I have more sympathy for ugly filenames than vague ones.
Screenshot 2026-09-13 at 10.03.18.png is not charming, but it tells me when the file appeared. image (14).png tells me only that thirteen other unnamed things got there first.
I would keep the timestamp and offer a small rename field in the capture preview. If someone types strange-door, append it. If they ignore the field, save the plain timestamp and move on.
I wouldn't have the tool add the window title automatically. It sounds useful until the title contains a person's name or a private project. The screenshot may already reveal too much. The filename doesn't need to repeat the leak in an attachment list.
I'd use that little field. strange-door is enough; the capture tool doesn't need to write a caption too.