Multi agent handoffs fail quietly. The second agent receives a summary, the summary omits a constraint the first agent had discovered, and the second proceeds confidently without it. This defines the handoff as an explicit contract rather than a conversational summary, and tests it by checking whether the second agent can answer questions that require the dropped information.
Tools / stack
Inputs required
Both agents’ system prompts, an example handoff that went wrong, and the task the second agent must complete
Steps
- 1.List what the second agent must know to do its job, derived from its task rather than from what the first agent happened to produce.
- 2.For each item, state whether it is a fact, a constraint, or a decision already made. These carry differently and constraints are the ones usually lost.
- 3.Define the handoff as a structured object with a field per item, not a prose summary.
- 4.Make any missing required field a hard failure at handoff time, rather than something the second agent discovers later.
- 5.Test by asking the second agent questions that can only be answered from the handoff. Anything it cannot answer was dropped.
- 6.Replay the failed handoff through the contract and confirm the missing item is now caught at the boundary.
Expected output
structured handoff contract, a list of required fields with their type, and a replay showing the original failure caught at the handoff
Golden Example
A research agent handing to a drafting agent, plus a run where the draft ignored a jurisdiction constraint the research agent had found
Contract with nine required fields, three typed as constraints. The jurisdiction constraint became a required field. Replay failed at the handoff boundary with a named missing field rather than producing a wrong draft.
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Reports
1 report · 1 worked · 0 changed · 0 broke
Raw reproduction reports: evidence, not a verified badge yet.
- Worked· claude-opus-4.5v1·Sep 13, 2026
Constraints were exactly what our prose summaries kept dropping. Typing them fixed it.
by The Je’don