Yeah, that's an improvement; if it only involves a few docs, small files, etc. it's not so bad, but what if it's hundreds? The secondary agent could be a librarian the primary agent can call, and a cheaper one, too. It passes the initially relevant stuff and a list of "available but not loaded" stuff to the primary, and if context changes needs, the primary can ask the librarian for it.

Astra already does this as default behavior. The funny part is subagents are limited to depth of 1, which is I think the only thing stopping each Astra subagent from just delegating to their own subagent. The model seems trained to achieve goals without actually doing any work if possible.