No matter how you put it Loki is the god of mischief, and mischief has an evil intent it doesn't matter if its the movie, the comic, or the ACTUAL mythology Loki is basically having evil intent at all times so he is looking for the answer yes in this debate.
As far as I know, Loki isn't actually a "Mischief God," or even a "trickster god," like the American god Coyote. He was mostly a "Fire-God." The idea is that, from the standpoint of the ancient Germanic tribesmen, you could never trust fire. Sometimes very helpful, sometimes very harmful, you could never turn your back on it. But, anyway, I don't know of anything in any of the Eddas (the poems and oaths that make up most of Germanic mythology) that call him anything but just his name. Some other German myths call him a fire god.
Mischief isn't necessarily evil. Evil is doing something purposely that is very wrong, while being mischievous is causing annoyance or slight harm. I don't think Loki is actually evil, but he's acts have gone beyond the point of being mischievous.