NotMeNotYou said:
The second part is correct, if you wish to edit the description to match the description on the original upload you're more than welcome to do so. The thing we forbid is writing made up crap to hope and influence the tags or other such nonsense.
If you do edit descriptions be mindful if the uploader is either the artist or the commissioner, you should let them deal with their descriptions in those cases.

Thank you! In that case I can safely say I've not been doing anything wrong, and that includes paying attention to the uploader to see if it's perhaps someone with more of a say in things than me. :)

That's a relief.