Your cat's visits to the litter box leaves behind some dangerous germs and bacteria on its paws. So allowing it to jump on kitchen counter tops can pose a health risk and contribute in spreading Toxoplasmosis.
Never put anything in your litter tray other than a good-quality, clumping cat litter. It should be cleaned out regularly, several times a day, and the whole tray should be renewed and cleaned at least once a week. Invest in a good litter scoop which will remove any stools from the tray completely.