ok i try to explai, how i do it.
you have your XYZ probe and the tool setter. and you have to have a referenced machine.
your XYZ probe is the master tool, let's say tool99.
put a fixed toollength of 100mm in tooltable for tool99.
-now you do a probing with the XYZ probe at the tool setter.
-after probing your read the machine coord for Z-axis and store it in a OEMDRO (for example 150mm)
-anounce tool99 to System by G43H99
-now you can do a z probing of workpice surface with XYZ probe and Zero z for G54
-now insert next tool in this example tool1 and do a probe at tool setter
-let's say tool1 probes at machine coord for Z-axis 140mm
now you know tool1 is 10mm shorter than mastertool99.
fixed toollength of mastertool is 100mm so toollenght for tool1 is 90mm.
now, if toollenght for tool1 (90mm) is entered in tooltable, and toollenght is set
via G43H1 Mach will compensate this.
all this can be done within a macro.
hope i was able to explain the difference between Auto Tool Zero and Tool Lenght Compensation.