Quite frankly, most tea bags from the market are toxic, so it would be best to cut the used tea bags open and incorporate the used tea leaves into the soil. [gardeningsoul.com]
I use loose tea, Assam and Darjeeling Broken, and dump the teapot outside of my kitchen porch. The Hostas love it. The tea is called Onno Behrends tea and is genuine Ostfriesen tea from Germany. It is drunk in little porcelain cups, with 2 pieces of rock sugar (Kluntje) and a splash of cream.
I put my used tea bags in the worm box, and the worms are still living and doing their thing. I've had the worm box going for at least 5 years, maybe longer.