A robotically controlled surgical tool including a lockout mechanism is provided. The surgical tool may comprise an instrument mounting portion. The instrument mounting portion includes a housing, a plate, a shaft assembly comprising an end effector, and a coupler to couple the shaft assembly to the instrument mounting portion. The end effector comprises a first jaw member and a second jaw member, the first and second jaw members defining a channel therebetween, and a blade slideably receivable within the channel to cut tissue located between the first and second jaw members. The surgical tool may include an actuation mechanism to actuate the end effector to provide reciprocating movement of the blade within the channel. A lockout mechanism is coupled to the actuation mechanism. The lockout mechanism may selectively enable reciprocating movement of the blade. An interface mechanically and electrically couples the instrument mounting portion to a robotic manipulator.