Discord, OBS, Nvidia GeForce Experience don't modify the game client. At most there's an overlay similar to steam. Though I suppose some people could argue Nvidia does since the tool allows you to change the game's display settings from outside the client. Similarly Third Party Tools could also include physical items like controllers or other input devices like MMO mice that have additional programmable buttons or things like the razer tartarus (something SE actually advertised a FFXIV version of a similar device on lodestone made by another company). As such these types of things should be safe. The tools they're looking at are the mods/trainers/tools that manipulate aspects of the game itself.