---
title: "Multi-agent systems, handoffs, and human approval"
chapter: "17"
---

# Multi-agent systems, handoffs, and human approval

Multiple agents can specialize, parallelize independent research, or provide
separation of duties. They also multiply latency, cost, context loss, security
surface, and nondeterminism.

## Useful patterns

- supervisor routes to bounded specialist agents;
- fan-out retrieves independent sources, then deterministic merge;
- reviewer evaluates an artifact against a rubric;
- producer/critic loop with a strict iteration cap;
- handoff transfers explicit typed state and evidence.

Do not create one agent per department merely to draw an impressive diagram.

## Handoff contract

Use a schema containing task, known facts, source IDs, actions completed,
uncertainties, remaining budget, and next authority. Do not rely on a prose
summary as the only state.

## Human-in-the-loop

Pause before payments, messages, record mutations, privilege changes, policy
exceptions, medical/legal conclusions, or irreversible work. The approval UI
must show exact proposed action, parameters, evidence, risk, and alternatives.
Approval must be scoped and expire.

## Separation of duties

The agent proposing an action should not be the sole validator for high-risk
work. Use deterministic rules, independent policy service, or authorized human.

## Failure containment

Give each agent the minimum tools and data. Use per-agent budgets, deadlines,
circuit breakers, and trace IDs. Cancel siblings when their output is no longer
needed.

## Feynman check

Adding agents is hiring more junior operators. They need job boundaries,
handoff forms, supervisors, budgets, and a rule for when a human must sign.