How should I set the bounding box of a robot link manually? The bounding box generated automatically by Klamp't can sometimes be undesirable.
Problem resolved: I posted the questions initially because the bounding boxes displayed in the RobotTest app are not aligned with some of the links' axes. After taking a closer look at the issue, I realized that the validity of collision detection is not affected by these seemingly wrong bounding boxes. ( This could just be some artifacts from the RobotTest app.)
Also, as have been suggested by Kris, I can use the function getBBTight in Python to get a tight bounding box to be used for collision detection.
You won't need to set a bounding box for any reason. If you want to get a tight bbox, you can call GetAABBTight() in C++ on the geometry, or getBBTight in Python.