Place the lime juice, mint leaves, raspberries, blackberries, blueberries, and agave nectar into a drink shaker. Muddle to release the juices from the berries.
2 tablespoons freshly squeezed lime juice, 10 fresh mint leaves, 10 fresh raspberries, 8 fresh blackberries, 8 fresh blueberries, 3 tablespoons agave nectar, 1 cup ice