Contrary to what some users will tell you, there isn't a required minimum number of tags. It doesn't matter if you have 5 tags or 50 tags; as long as you've thoroughly tagged all the visible details in the image, that is sufficient. Adding irrelevant tags in order to reach an arbitrary minimum is neither necessary nor desirable.
In particular, this post should not be tagged writing. Please read the definitions of unfamiliar tags before using them.