E4 · Handoff
Family: Multi-agent
Only one agent is active at a time; it hands control over entirely to a better-suited agent, which becomes the point of contact.
Principle
Only one agent is active at a time. When another is better placed, it hands over full control and the conversation state, then steps aside. The new agent becomes the user’s point of contact.
The problem it solves
The right specialist only shows up mid-conversation: routing done once, on arrival, is no longer enough.
When to use it
- Conversational triage, for example in customer support: you find out mid-conversation which specialist fits.
- You want a specialist to take over part of the conversation entirely, rather than being called like a tool by a central agent (E1).
When to avoid it
- The target agent can be deduced from the input: deterministic routing (B2) is simpler and cheaper.
- The risk of transfer loops is real (Microsoft): without a safeguard, two agents can keep bouncing the request back and forth.
Common pitfalls
The anti-patterns that misuse this pattern, best established first. Each sheet describes the symptoms, the public incidents and the remedies.
Framing and choice of level
- AP03 · LLM for a deterministic decision — The model decides what a rule, a parser or a linter would get exactly right, almost for free.
Context and memory
- AP27 · Lost in conversation — The request arrives in pieces; the agent commits on the first one and never backtracks.
- AP32 · Miscalibrated handoff context — A summary that loses what matters, or a raw history in which the subagent claims another agent’s actions as its own.
Loop, stopping and orchestration
- AP35 · Unbounded agent loop — Nothing in the code stops the agent: no turn cap, no budget, no deadline.
- AP39 · Unchecked propagation — One agent’s output becomes the next one’s input unchecked, and a local error ends up in the deliverable.
Security and permissions
- AP69 · Implicit agent-to-agent trust — Agents discover each other and delegate tasks by default: a modest agent can recruit the most powerful one.
Oversight, operations and governance
- AP73 · Premature human removal — Human teams are cut on the agent’s early numbers, and complex cases come back later, and angrier.
- AP74 · Unowned customer-facing agent — The agent speaks for the company, makes up a policy, and the company finds out it is bound by what it said.
Synonyms by vendor
- Handoff, routing, triage, transfer, dispatch, delegation (Microsoft)
- Decentralized pattern (OpenAI)
- Handoffs (OpenAI Agents SDK, LangChain)
- Peer-to-peer (Google (Agents Companion))
- Agent transfer (Google ADK)
- Swarm (passages de relais entre pairs) (AWS Strands)
Neighbouring patterns
Sources
- A practical guide to building agents — OpenAI, 2025-04-17
- Multi-agent (LangChain v1) — LangChain
- AI agent orchestration patterns — Microsoft, Azure Architecture Center, 2026-02-12
Content reviewed on 2026-10-02