1) If you use clay pots, DO NOT paint them. Use unglazed, unpained pots so that when they get wet, they provide a cooler and wetter environment inside. Sealing the clay undermines this process.
2) You can make a much better amphibian home with a mulch pile. It will host a whole detritus food chain. Toads and other beneficial creatures can hide in there during hot, dry, or cold weather.