The message to customize tool links seems rather odd in that it needs two open brackets and one closing bracket. Is that intentional?
I tried creating w:en:MediaWiki:Checkuser-investigate-compare-toollinks but it doesn't appear to work. Unless I've formatted it incorrectly – there's an extra bracket in the one on meta that I assumed is a typo.
Oh nevermind, the links require two square brackets at the start and one at the end in order for it to work. That's quite strange.