I can tell you right now that they don't hold humidity at all and barely any heat. I use it for my crocodile gecko, and I had to block off all sides to keep humidity decent (I made a custom background and covered the other sides). Though some people use them for chameleons, so I guess you could try it. I'm not sure on the humidity needs of tokays, but if they're high, you'd probably need a mister or something.
~Maggot