Is there a way to write tag descriptions in the meta part of this SE? I tried doing that just now and I don't seem to be able to (whereas on the main SE there is no problem with that).
Unfortunately, tag-wiki creation / editing is not supported on the meta sites at present:
We're not currently allowing tag wikis to be edited on metas, as we plan to push out the shared meta tag wikis from meta.so.
This may change in the future.