Options --> general --> Update tags when file info changes
Options --> file location --> also store image in the file's tag
These would disable tag writing completely.
e-head,
You can disable writing the ID3v2 "popularimeter" aka the Rating field separately in the field specific options.
- explained by the user Doof:
And actually... I just remembered that you can also customize this on a per field basis. By default they're all set to write to file tags, but you can turn it off for whichever fields you don't want MC to touch. To do that, go to Tools->Options->Library & Folders and then pick either "Standard Library Fields" or "User Library Fields". Then pick the field in question, select "Edit This Field" and clear the checkbox for "Store in file tags (when possible)". So if you wanted, you could uncheck that for everything but BPM and ReplayGain for instance.
The tool name and version comments can be disabled only by disabling the main Comment field. However MC writes these fields only when some other tags are written too. So if you deliverably change e.g. the Album tag it should not matter if the "tool" tags get updated.
Personally, I have a problem with linking external cover art. Changing cover art links (only in the library) forces me to constantly update my backup sets because MC unnecessarily rewrites the file tags each time the cover art link is changed. An older MC version didn't have this problem - if only external cover art links were changed the audio files were not altered.
I have explained the problem and suggested a solution here:
http://yabb.jriver.com/interact/index.php?topic=45977.0.
My workaround is to change the global tagging option before adding or changing cover art, but that is quite irksome and sometimes I forget to do it.