Study finds deep agent hierarchies preserve context but lose findings

A trace study models how findings survive through multi-agent delegation trees. Across 600 production research traces, each extra layer loses information, and one in sixteen annotated handoffs drifts off target. Two tiers beat a flat agent on cost only above roughly 403 findings under the measured parameters. A separate 743,819-tool-call analysis finds that production agents delegate early rather than in response to a filling context.

For teams designing multi-agent workflows, hierarchy depth should be a measured budget decision rather than a default architecture. Keep fan-out wide, summaries explicit and depth small unless the task is large enough for context cost to dominate. The underlying production corpus is not released, so the numerical threshold needs local validation.