A minimally invasive surgical tool comprising: an instrument shaft elongated along an instrument shaft axis; a driveshaft (380, 392) mounted to the instrument shaft for rotation about a driveshaft axis that is offset from the instrument shaft axis; an end effector coupled with the instrument shaft so that an orientation of the end effector can be varied relative to the instrument shaft about a pitch axis and about a yaw axis, wherein the end effector comprises an articulated feature; a driven shaft (382, 396) coupled with the articulated feature for articulation of the articulated feature via rotation of the driven shaft relative to the end effector around a driven shaft axis; and a coupling member (384, 394) coupling the driveshaft with the driven shaft so that a rate of rotation of the driveshaft and a rate of rotation of the driven shaft are equal when the driveshaft axis and the driven shaft axis are non-parallel, wherein: the coupling member comprises a coupling member first end and a coupling member second end with a coupling member axis defined between the coupling member first end and the coupling member second end; the driveshaft is axially and rotationally coupled with the coupling member first end so that rotation of the driveshaft about the driveshaft axis produces rotation of the coupling member about the coupling member axis; and the driven shaft is axially and rotationally coupled with the coupling member second end so that rotation of the coupling member about the coupling member axis produces rotation of the driven shaft about the driven shaft axis, wherein the driveshaft engages the driven shaft so as to maintain equal angles between the driveshaft axis and the coupling member axis, and the driven shaft axis and the coupling member axis when an angle between the driveshaft axis and the driven shaft axis varies during rotation of the driveshaft and the driven shaft. a driveshaft (380, 392) mounted to the instrument shaft for rotation about a driveshaft axis that is offset from the instrument shaft axis; an end effector coupled with the instrument shaft so that an orientation of the end effector can be varied relative to the instrument shaft about a pitch axis and about a yaw axis, wherein the end effector comprises an articulated feature; a driven shaft (382, 396) coupled with the articulated feature for articulation of the articulated feature via rotation of the driven shaft relative to the end effector around a driven shaft axis; and a coupling member (384, 394) coupling the driveshaft with the driven shaft so that a rate of rotation of the driveshaft and a rate of rotation of the driven shaft are equal when the driveshaft axis and the driven shaft axis are non-parallel, wherein: the coupling member comprises a coupling member first end and a coupling member second end with a coupling member axis defined between the coupling member first end and the coupling member second end; the driveshaft is axially and rotationally coupled with the coupling member first end so that rotation of the driveshaft about the driveshaft axis produces rotation of the coupling member about the coupling member axis; and the driven shaft is axially and rotationally coupled with the coupling member second end so that rotation of the coupling member about the coupling member axis produces rotation of the driven shaft about the driven shaft axis, wherein the driveshaft engages the driven shaft so as to maintain equal angles between the driveshaft axis and the coupling member axis, and the driven shaft axis and the coupling member axis when an angle between the driveshaft axis and the driven shaft axis varies during rotation of the driveshaft and the driven shaft. the coupling member comprises a coupling member first end and a coupling member second end with a coupling member axis defined between the coupling member first end and the coupling member second end; the driveshaft is axially and rotationally coupled with the coupling member first end so that rotation of the driveshaft about the driveshaft axis produces rotation of the coupling member about the coupling member axis; and the driven shaft is axially and rotationally coupled with the coupling member second end so that rotation of the coupling member about the coupling member axis produces rotation of the driven shaft about the driven shaft axis, wherein the driveshaft engages the driven shaft so as to maintain equal angles between the driveshaft axis and the coupling member axis, and the driven shaft axis and the coupling member axis when an angle between the driveshaft axis and the driven shaft axis varies during rotation of the driveshaft and the driven shaft. the driveshaft axis and the coupling member axis, and the driven shaft axis and the coupling member axis when an angle between the driveshaft axis and the driven shaft axis varies during rotation of the driveshaft and the driven shaft.