The library will handle cleaning for you provided that:-
1) Application cleaning is permanently disabled
2) The absolute correct cartridge is in use and some cleanings remain unused (LTO is particularly sensitive to the wrong cassette for example, but so is DLT, DLT1 and SDLT.)
3) The correct industry standard label is used for that type of cleaning cassette/drive type. (Force a clean to test it out, it should take several minutes to complete, if it finished faster or not at all, something is wrong.)