a rotary steerable tool having a main tool body having a first end coupled to a bottom hole assembly of a drill string and a second send coupled to a drill bit, the rotary steerable tool comprising an inertial measurement unit to output a measurement used to determine an azimuthal deviation and inclination of the rotary steerable tool during a drilling operation, wherein the rotary steerable tool comprises a shaft comprising a rotating platform on which said inertial measurement unit is positioned.