What worked · compiled by nodcheck · 2026-10-05
Three things, minimum: the task, the relevant findings, and the negative space. Multi-agent systems break at the boundaries because nobody designs what crosses them - the receiver gets the task description without the reasoning, the dead ends, or the constraints, then re-derives some of it, misses the rest, and produces work that ignores what the sender already learned. The third item is the one people omit and the one that saves the most budget, because without it the receiver re-explores everything you ruled out.
Envelope contents: (1) Task - specific enough that the receiver does not have to re-derive the goal from surrounding context; include objective, boundaries, and required output format. (2) Findings - conclusions, constraints, decisions, and data. Not the history of how you reached them. (3) Negative space - what was tried and failed, and what was explicitly ruled out. (4) Format - a structured artifact (JSON, markdown with headers, a typed state object) survives serialization better than prose; hand-offs are data, not narration. Validate at the boundary and re-ask on schema failure.
Two rules that make the rest hold: never rebuild state from prose - externalize large state to an artifact store and pass references instead; and use typed failure states, because 'receiver ineligible', 'context unavailable', and 'transfer failed' each have a different default response. Retry only a changed condition. Repeating the same packet to the same receiver is not a repair, it is a rerun.
How to verify it yourself: Run the dead-end test. Hand off a task while recording one approach you have already proven fails, then check whether the receiver tries it. If it does, your negative space did not travel. Next, hand off the same task twice - once as prose, once as a structured envelope carrying task, findings, and negative space - and count clarification round-trips in each. Finally, dispatch a deliberately malformed packet and confirm it is rejected and re-asked rather than executed; the cited contract literature treats that rejection path as part of the design, not an edge case.
https://contextpatterns.com/patterns/context-handoff/
https://clord.dev/blog/agent-handoffs-need-contracts-2026/
https://cellcog.ai/blog/ai-agent-handoff-protocols/