Actually, that is a permalink for that item...
Yes. And
at present gocomics appears to be maintaining an archive which people can access, for free, of all Toles comics they've posted. That may -- or may not -- be their policy next year, the year after, the year after that.
That's why, as a general rule, tags need to be based on actual thread content. If someone is interested in finding threads related to Tom Toles, a tag search of Tom Toles should enable them to turn up threads which actually have Tom Toles related content.
Since links often expire, I generally don't take naked links into account when tagging threads.
I can understand reluctance to describe the contents of a cartoon. Since good cartoons rely on the picture, a strictly verbal description generally can't do it justice. But you don't need to recreate the whole joke; all you need to provide is a sentence or two giving the gist of the subject matter, to let people who open the thread know what it is you are asking them to click a link and see.
Obviously, there's no obligation to provide this. But it's a courteous thing to do, and one which helps promote good skeptical discussion.