If a label says its VEGAN, it's vegan.
Agar agar and irish moss are vegan gelatins. Agar is made from a japanese seaweed as far as I remember.
You just need to actually read the ingredient list. As you should always check with anything that says "vegetarian". If there's no animal products (gelatin, glycerine, etc) then its fine. Though I think you can get veg-based glycerine, but it should say.
ALSO: many products will not say specifically agar, a lot of them will say "gelatin" or "glycerine" and either in (brackets) beside it say "vegetable" or "vegetarian" or somewhere on the label will say *all ingredients vegetable sourced, and will often have a V logo on it.
What products are you looking for anyway?
And one of the questions you can ask is "Is it animal sourced?" Thats a little more specific than asking if it comes from an animal.