The title should do a good job of summarizing the main question. It shouldn't just be a few keywords or just the overall topic you're asking about (e.g. "timestamps"); rather, anyone reading the title should be able to get a sense of the overall question you're asking.
Sometimes, a clearer title may be shorter than an overly long and detailed one. That said, ideally you should be able to write a title that's both descriptive and clear. It doesn't necessarily need to be phrased as a complete sentence/question, but I personally prefer titles to be phrased as questions whenever possible (i.e. unless it makes the title really unwieldy or unclear).
If you see a question by another user with a vague or unclear title, feel free to edit the post to improve it. (That said, you should generally avoid very minor edits; if you're editing a post, you should try to improve the post as much as possible, fixing all errors you see.)