If you make a Tag Wiki entry, you can use the markdown backticks to show something is a tag (as is done quite often on these sites) and it shows it on the Tag info page. If you then go to the Tag Questions page, it just shows normal backticks.
Tag Info Page:
Tag Questions Page:
Here is a screenshot (Tag Info Page) showing that brackets are stripped out also:
EDIT: It would also be great if the new tag posting feature would work for tag wikis. Then it could look like so:
The excel tag is used for referencing the Excel spreadsheet application from Microsoft. If your question is about VBA then also tag it vba. If it is about an Excel formula or worksheet function, then tag it worksheet-function.