It has been discussed briefly in earlier books but great detail in the 7th book that Harry's Invisibility Cloak is one of the 3 hallows and hides its wearer truly and completely.
It's not any Disillusionment Charmed object whose power will fade with time. It remains as good as new even used repeatedly through generations. In other words, it was intended in the 7th book that there is no other clock that is as powerful and efficient in hiding the wearer as that of Harry's Invisibility Cloak.
Yet, in book 4, Moody's magical eye was able to see through it. I mean if we are talking about legendary Hallows like Elder Wand & Resurrection Stone and we put an Invisibility Cloak on the same platform - infact the cloak was termed as even more powerful than the other 2 hallows - and still some wizard wearing a magical eye, which later was then abused by evil Doloris Umbridge, was able to see through it with apparent ease!
Does it really justify the notion of the cloak that IT HIDES ITS WEARER TRULY AND COMPLETELY?