Lead params
Sharpness, contrast, brightness.
(acrylyc optic isn't good here).
...
There could be a lot of params, but actually you can't understand is it good or not for you before use it in real.
Because even so respectable words like "glass optic lenses", "aplanat", "CA correction", "full coated lenses"
- could be just misprint. And quality of lenses doesn't depend on this words.
Sharpness, contrast, brightness - you can't see this in product description.
So all you can do - see it in real or searching for reviews etc.
Don't forget that when you buy in a store, you can check for defect can compare etc.
All helpful you can see in description:
- magnification power
- field of view (rare)
- diameter of lenses\ocular (rare, frequently wrong)
- weight
And if you wear glasses (-D) working distanse (between lenses and object) is shorter.