The agg expression:

{
    $and: [
        {$lte: ["$age", NumberInt(12)]},
        {$gt: ["$age", NumberInt(15)]},
    ]
}

Currently produces two separate one-sided ranges. This means that lots of work will be done server-side for a query which is known to return no results on the client. Query analysis should optimize this predicate to produce a single encrypted payload that contains no edges.

Note that this optimization is only valid without arrays.