Not good enough. Elf ears, cat/other animals ears, horns or minor non-human characteristics shouldn't be tagged as monster girl. The fetish requires more than that.

Love the Unloved

this tag pretty much useless as a monstergirl fetish finding tool as nerds have tagged anyone with so much as horn or a snaggletooth.

Why is there no tag for "Monster Boy"?

A Xenomorph from Alien franchise would also fit under this description... I recommend looking up tag wiki on e621, in 99% of cases they've already done the hard part (thinking) exceptionally well. This particular tag is aliased under "monster girl (genre)" if you're looking for it. Oh and horrible formatting.

This should be changed to mythological female creatures with a humanoid appearance, instead of just non human females. An android would fit into the former that you suggested. When they are not monsters

what about this tag https://nhentai.net/tag/demon-girl/