the Toys2Go stainless pannier racks are designed - both sides - to take tool tubes IF needed; the 5L fuel bracket that takes a 5L plastic fuel cell can ALSO do duty as a tool tube carrier;
and the tool tubes on it's own will bolt directly to the OUTSIDE of the pannier rack, as well as the INSIDE (caution: the rising swing-arm may well interfere with the tool tube, always CHECK!)
it bolts up to the two tabs welded on to the edges of the T2G pannier rack.
Having said all that, the benefit of an ANGLED-up tool-tube (not shown here) are that tools, if SLIGHTLY loosely packed, do not 'shunt' backwards and forwards every-time you approach a traffic light!!!
will try and post some pictures here:
Chris