Does anyone know if this is on the cards at all? It really would be awesome having it - not just for tags (so info on the tag’s page) but for the additional information it could provide in posts.
We often come across posts which mention (or sometimes have links to) things that we also have tags for - and I believe if tags also include info (short description and a link) I am sure far more people would include them in posts (far easier than finding the web page then copying and pasting a link). This would in turn help provide valuable information to readers of the post.
For example here on Discouse one of the most popular tags is #gdpr (82 topics) but many people won’t know what it is. By having this extra info available right there is highly convenient for the user, they could even click on the external link for extra info. It would also be useful for other popular tags her like #docker, #onebox, #akismet, #ember, etc.
I’d really love to see this and I think it would be highly valuable to Discourse - if I knew Ember I would offer to submit a PR 
(the Rails side is easy enough - it’s just a few extra fields).
I would go with something like the following fields:
desc
external_link
external_link_count
topic_id
topic_id_count
To count clicks as well as I think people love seeing that. Included topic_id in case there is an important Topic about that tag too, as there often is.
(Is it worth moving this post to a separate Topic?)