We sympathise with other commenters who found this to be a bit sour/tart. To address this, we toyed with the idea of flipping the volumes of the liqueurs but concluded that this would do harm to the 'idea' of the cocktail. So we decided that the shortest distance between two points lay in the direction of our bottle of agave syrup, from which we added just 2.5ml. Much better for us. And we agree with other commenters that a splash of mezcal doesn't go astray.