Add ricotta and ¼ cup of the agave syrup to a medium mixing bowl. Whisk vigorously until the mixture is lighter and fluffy. Evenly spread the whipped ricotta on each slice of toast. Evenly distribute the walnuts and Craisins on top of the ricotta. Drizzle over the top any remaining agave syrup and garnish with the thinly sliced mint and salt. Serve immediately with a side of fresh berries.