Making custom enchantments tradeable by librarians

So I have 2 custom enchantments, Agility and Lengthening and I want to make them tradeable. I have my "tradeable.json" in data -> minecraft -> tags -> enchantment and the contents is just 
{
    "values": [
        "better_tridents:lengthening",
        "better_tridents:agility"
    ]
}
Is this the right way to do it?