insufficient

> A cached POST response can be reused to satisfy a later GET or HEAD request. In contrast, a POST request cannot be satisfied by a cached POST response because POST is potentially unsafe; see Section 4 of [CACHING].

So if you are using POST to query, you can't cache the response. You have to resort to POST/GET. With QUERY, you have idempotent requests with cacheable responses you can directly return.

Cache-Control and Content -Location.