In a small bowl, whisk together the flour, cream of tartar, baking soda, and salt. Set aside.
In a large bowl, use an electric mixer to cream the coconut oil, sugar, and eggs. Add the dry ingredients 1/3 at a time, and mix to incorporate well.
In a very small bowl, stir together the sugar and cinnamon for the topping. Shape the dough into one-inch balls, flatten slightly, then dip each ball into the cinnamon sugar to coat evenly. Place each cookie on a parchment-lined baking sheet, making 3 rows of 3 cookies each (9 cookies per sheet).
Preheat the oven to 350 degrees. Refrigerate the unbaked cookies while the oven is preheating to keep them from getting too flat in the oven.
Bake for about 12 minutes, until the cookies are set and beginning to crack. Cool on a wire rack.