A wellbore tubing string assembly comprises: a string including an inner bore having an inner diameter and a plurality of tools installed along the string including a first tool and a second tool axially offset from the first tool along the string; the first tool includes: a first sleeve in the inner bore having an inner surface, the inner surface defining a first restriction diameter smaller than the inner diameter; a first sensor mechanism in communication with the first sleeve and responsive to an application of force against the first sleeve; the second tool includes; a second sleeve in the inner bore having an inner wall surface, the inner wall surface defining a second restriction diameter smaller than the inner diameter; a second sensor mechanism in communication with the second sleeve and responsive to an application of force against the second sleeve; and a sealing device having a diameter greater than the second restriction diameter and being deformable to be pushable through the second restriction diameter to apply a force against the second sleeve.