As stated by fixer external is a meta tag, meaning that it does nothing to clarify the problem except when used as a modifier for other tags. Tags should be clear, well defined and accurate rather than requiring a list of them to nail down the problem.
If a tag can be applied to almost anything then it is a good target for burnination.
A short list of the uses of external:
The list of abuses go on.
Preferably where possible questions should be tagged properly, but the most egregious abuses of external should simply have the tag deleted.
Most obvious candidates for tags:
