I feel like the tail_sex tag is rather vague, as it generally includes any acts of sex with a tail, in forms of tail penetration, tail being penetrated, and tail insertion. I don't see any particular way to specifically search for tail insertion images such as #1867020 without also finding images like #456281.

thumb #1867020 thumb #456281

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post #1867020 post #456281

https://e621.net/wiki/show?title=tail_sex

The current wiki seems pretty well built for it, tail_sex seems to be intended for instances where the tail is being used as a pseudo penis, though with tail_job being also implicated to it that sort of takes away from it... perhaps the aliases should be re-worked and tail_sex should become an umbrella tag that gets implicated to all sexual acts with a tail.