There is basic auto-completion suggesting table field names if the table type is known. Though it's really basic. Take this example.
---@param a { foo: { bar: number } }
function buz(a) end
buz({
foo = { -- `foo` is suggested
bar = 0 -- `bar` is not
}
})
a is a nested structure, meanwhile foo is suggested by the language server, bar is not. It might be handy to have such suggestions.