Right now, in chat, we can use
[meta-tag:tagname]. But in MSE chat, I think it would be useful to reference a tag on any site through this format. For example:
possible reasonably doable? Since they only render as a link (it doesn't fetch number of tagged questions or any other data), I don't imagine it would be difficult.
EDIT: Building upon this question, I think the proposed markup should be valid in descriptions as well.