A downhole tool in a drill string for mitigating hazards of a blockage in an annulus of the drill string. The downhole tool can sense blockages and selectively recirculate flow from within the annulus back to surface. Further, the downhole tool is made up of segments that are selectively detachable from one another, so that the segments above the point of detachment are removable from a wellbore. The bypass assembly includes a sleeve in the downhole tool with openings in its side; when the annulus reaches a set pressure, the sleeve slides to a position so the openings register with ports formed through a side of the tool to allow bypass flow. A processor in the downhole tool senses movement of the string, and when the string is axially stationary more than a designated period of time, the processor emits signals to detach the segments.