tortoisetrust.org/articles/lighting.html
I know, I know frogs and turtles have different care requirement. But even if they dont "need" uvb as much as a reptile like a tortoise or turtle or even iguana. I think they will benefit from having SOME uvb/uva put off onto them. Just take a look at that article. Of course this only applies to diurnal creatures or if you wish it to be more natural. You know like getting a full cycle. For my terrarium Iam sure I am going to give off some uvb. Even if the toads hide during the day. Just some food for thought. If the animal is hidden in leaf litter in nature. Or digs under the earth a few inches deep. Iam sure they still soak up some rays, not as much as they would be if fully exposed but still enough.

This is out of what I think.

Hopes this help.