I'll preface that I'm someone who uses a lot of external tools, personally save reading, seed finding tools, altering saves, etc. so I have a fair bit of experience with this type of stuff.
I'm absolutely echoing the sentiment that it's personal preference, whatever you feel like is 'cheating' or fair use in your own saves. I personally allow the use of basically any tool on unrestricted files, but also sometimes have files where I avoid it all which are plenty fun in their own right. In singleplayer anything is free game, though for some actions you should probably tell people what you used so that they can understand/it makes sense.
I will say, there are a couple scenarios where they could be considered cheating, basically anytime you shift from singleplayer to any sort of comparisons or competition.
1. Speedrunning, if you want to speedrun and properly compare times/submit times to the leaderboards, there are strict (but few in number) rules you have to follow, of which the banning of external tools or restriction to separate categories is the norm.
2. When playing with others, keep your use of the tools open, I'm not saying they aren't allowed, that's up to you all as it's up to you on a singleplayer save, just be genuine about using them and consider not if they don't want you to, you are a collective in multiplayer.
Otherwise go at it, and draw the line where you want. That could mean using all, some, or no tools at all, and that's fine, whatever results in the most fun for yourself.
