I realize that this is a bit picky, but the joist tool properties Material Size, Material Type, and Material Length should be renamed as Joist Size, Joist Type, and Joist Length. Material size/type/length should probably be reserved for the actual material being supplied (product properties).
For example, if the joist tool spits out some joists @ 30' and I only stock 32' material, 30' is the Joist Length and 32' is the Material Length.
Thanks for the input & example, John! I'll send this to the team for further discussion.