Good tag to add, just needs to be generalized to a noticeable age difference ligge @M8 GTE said, you can do things like -tag:"lolicon" and -tag:"shotacon" if you don't want that. Blacklist them even, you have full control over what you see on this website.

I think a better definition would be "Two partners with noticeable age difference." For example a common age gap pairing is a man in his fifties with a woman in her early twenties.

I think this is a necessary tag and it's likely to become more popular (because it's becoming a specific paraphilia about adults— it doesn't fit in Chronophilia). The definition is on the right track, but specifically I think it should be: 'depictions of age gap relationships between adults of either sex' JP is well ahead here, search '年の差' or 'Toshi no Sa' for example works. The necessity of this tag is also because there is variation look at just 'の差'' [i.e. no sa] to find variant age gap titles. This also makes it very annoying to search because look how common 'age' is in JP/EN words and look at how possible searching 'no sa' is without kanji.

This is a tricky tag to define, but this tag will be more useful if the definition includes what is considered an "age gap". Excluding shota/loli might make it a bit easier to define, but there are other was to exclude them i.e. -lolicon. If not a minimum number of years then perhaps a "noticeable difference in age" or "an noticeable difference that plays a part in the narrative" or "interaction between characters of different developmental/life stages".

just remove shotacon and lolicon from the search. No reason to create 2 tags for the same thing