Vinegar is very good at leaving clean, streak-free glass. It will remove the mineral deposits too. If a lot of deposits are built up (as in a tank that has been used as a fish tank) it may take more than one application. Soaking it and/or using hot vinegar will help (be careful you don't get it too hot & crack the glass).

I like vinegar because it is all natural and also has disinfectant properties. I do recommend rinsing and/or allowing it to dry & air out thoroughly before you put your snake back in just because the odor is pretty strong, but as far as I've been able to determine, it is not harmful.

One possibility if you have marks on the glass that the vinegar won't remove is that the glass has become etched. I don't really know details about how or why this happens, but the smooth surface of the glass gets damaged somehow and once that happens I don't think anything short of melting the glass & remaking it will remove the dirty appearance.