In this paper, a method for the optimal design of metamorphic manipulators is presented, using path dexterity indices in diverse service tasks. The Swedish massage service is chosen as an application, due the very dissimilar techniques that can be challenging for fixed anatomy manipulators. These techniques are presented and a mapping to dexterity indices is proposed based on each technique's requirements. A method for the evaluation of metamorphic anatomies over tasks is proposed, and the optimized anatomy of a metamorphic manipulator is determined. Finally, an illustrative example is presented for three tasks, where the advantages of the anatomy optimization are demonstrated.