I'm with you Karen. The coffee grounds add organic material to the soil which help it to retain moisture and nutrients, but don't have much in the way of nutrients that plants can use.
Caffeine is a stimulant for humans and other animals including insects, but not for plants. It might be toxic to insects in the soil, though, which might help the plant a little bit.
I'd recommend you do a science fair project next year where you add coffee grounds to one tomato plant in a pot, and no coffee grounds to another. Water and fertilize the same for both and see if there's any difference after about a month. (obviously too late for this year)
