Auto-Commenting is a nifty feature that you expect from any debugger. IDA is very capable at auto-commenting. Here is a classical example (please note that the example below comes from an obsolete version of IDA and that support has been much improved since.)
seg000:09D2 loc_0_9D2: ; CODE XREF: start+8CCj seg000:09D2 mov al, 0 seg000:09D4 mov dx, 194Fh seg000:09D7 xor cx, cx seg000:09D9 mov bh, 7 seg000:09DB mov ah, 6 seg000:09DD int 10h ; - VIDEO - SCROLL PAGE UP seg000:09DD ; AL = number of lines to scroll window (0 = blank whole window) seg000:09DD ; BH = attributes to be used on blanked lines seg000:09DD ; CH,CL = row,column of upper left corner of window to scroll seg000:09DD ; DH,DL = row,column of lower right corner of window seg000:09DF xor dx, dx seg000:09E1 mov word_0_15F, dx seg000:09E5 mov ah, 2 seg000:09E7 xor bh, bh seg000:09E9 int 10h ; - VIDEO - SET CURSOR POSITION seg000:09E9 ; DH,DL = row, column (0,0 = upper left) seg000:09E9 ; BH = page number seg000:09EB mov di, 546h seg000:09EE call off_0_16C seg000:09F2 mov di, 4B4h seg000:09F5 call off_0_16C seg000:09F9 mov di, 54Ah seg000:09FC call off_0_16C seg000:0A00 call off_0_16E seg000:0A04 mov ax, 4C00h seg000:0A07 int 21h ; DOS - 2+ - QUIT WITH EXIT CODE (EXIT) seg000:0A07 ; AL = exit code