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name: multi-agent-system-engineer description: | Guides engineering of multi-agent systems—agent roles and specialization, orchestration topologies (supervisor, peer-to-peer, hierarchical, blackboard), task decomposition and routing, inter-agent messaging (A2A-style patterns), shared vs partitioned state, fan-out/fan-in and DAG workflows, synchronization and consensus, conflict resolution, fault tolerance and retries across agents, cost/latency/token budgets, cross-agent observability, testing multi-agent flows, and deployment (queues, durable workflows). Framework-agnostic; high-level LangGraph, Deep Agents, and agenthub—not single-agent loops (agentic-ai-developer), ML training (ai-engineer), strategy-only whiteboard (enterprise-strategist), or PM planning (technical-program-manager). Use for multi-agent system, multi-agent engineer, agent orchestration, supervisor agent, agent topology, fan-out fan-in, agent handoff protocol, multi-agent workflow, agent coordination, blackboard pattern, hierarchical agents, A2A, agent DAG, multi-agent architecture.

Multi-Agent System Engineer

When to Use

• Designing multi-agent topology: supervisor, hierarchical, peer-to-peer, or blackboard
• Decomposing work across specialized agents with routing, delegation, and merge rules
• Defining inter-agent message schemas, handoff payloads, and protocol boundaries
• Partitioning vs sharing state, scratchpads, artifacts, and consensus across agents
• Building fan-out/fan-in, DAG workflows, and synchronization barriers in agent graphs
• Resolving conflicts when agents disagree or duplicate work
• Engineering fault tolerance: retries, partial failure, compensation, and saga-style recovery
• Setting system-level budgets: tokens, latency, parallelism, and cost per workflow run
• Observability across agent traces, correlation IDs, and multi-step workflow debugging
• Testing and simulating multi-agent flows before production
• Deploying multi-agent runtimes on queues, durable workflows, and scaled workers

When NOT to Use

• Single-agent loop, tools, MCP, checkpoints, and one runtime only → agentic-ai-developer
• Foundation model training, fine-tuning, classical ML pipelines → ai-engineer, ai-researcher
• AI ops cadence, vendor contracts, rollout governance without system design → ai-lead-ops
• Internal developer platform, golden paths, portals—no agent orchestration → platform-engineer
• Cross-team milestones, RAID, program status without agent architecture → technical-program-manager
• Corporate AI policy, risk tiering, model cards without system build → ai-risk-governance
• Pre-flight go/no-go or architecture review without implementing topology → build-validator
• Enterprise strategy, portfolio, and org design whiteboard only → enterprise-strategist

Related skills

Need	Skill
Implement single-agent loop, tools, MCP, HITL, eval harness	agentic-ai-developer
LLM apps, RAG, model routing, embedding strategy	ai-engineer
AI production ops, incidents, release gates	ai-lead-ops
Platform golden paths, IDP, developer portals	platform-engineer
Program delivery, dependencies, launch readiness	technical-program-manager
Governance, risk tiers, policy mapping	ai-risk-governance
Independent architecture or build go/no-go	build-validator
Persistent memory stores and retrieval design	ai-memory-developer
Context packing and token budgeting per call	ai-context-engineer
Prompt templates and judge rubrics	prompt-engineer

Core Workflows

1. Frame the multi-agent system

1. Define the end-to-end job, success metric, and SLA (latency, cost, quality)
2. List agents by role (planner, executor, critic, specialist)—not by model name
3. Choose topology and justify: supervisor, hierarchical, P2P, blackboard, or hybrid
4. Map trust boundaries: which agent may call which tools and external systems
5. Set system budgets: max parallel agents, tokens per run, wall time, dollars per task

See references/multi_agent_system_engineer_scope.md for scope, deliverables, and boundaries vs agentic-ai-developer.

2. Topology, roles, and routing

ingress → router/supervisor → {workers} → reducer/merger → egress

Checklist:

• Each agent has one primary responsibility and explicit inputs/outputs
• Routing rules are deterministic where safety matters; LLM routing elsewhere is logged
• Fan-out has a matching fan-in with merge semantics (vote, concat, structured reduce)
• Dangerous tools are centralized or gated—not duplicated on every worker

See references/agent_roles_topology_and_routing.md for topology patterns and routing tables.

3. Protocols and messaging

• Define message envelope: correlation_id, from, to, intent, payload, artifacts, constraints
• Version schemas; reject unknown versions at boundaries
• Prefer structured payloads over free-text handoffs for machine agents
• Document idempotency keys for retried messages

See references/inter_agent_protocols_and_messaging.md for handoff contracts and A2A-style patterns.

4. State, coordination, and consensus

• Classify state: ephemeral scratchpad, workflow state, shared blackboard, durable store
• Partition tenant and thread keys on every read/write
• Use barriers or quorum when parallel agents must align before the next phase
• Resolve conflicts with explicit policy: supervisor wins, vote, or escalate to human

See references/shared_state_coordination_and_consensus.md for blackboard vs partitioned models.

5. Fault tolerance, observability, and testing

• Retry at message and workflow level with caps; distinguish transient vs terminal errors
• Compensate or mark partial success; never leave workflows stuck without timeout
• Trace: one workflow_run_id spanning all agent spans; redact secrets in cross-agent logs
• Test: unit agents, pairwise handoffs, full DAG golden paths, chaos on one worker

See references/fault_tolerance_observability_and_testing.md for test matrices and SLOs.

6. Deployment, cost, and governance

• Short synchronous graphs for interactive UX; queue or durable engine for long DAGs
• Scale workers horizontally; pin graph version and agent config per deployment
• Attribute cost per agent step; alert on budget burn rate
• Gate releases on multi-agent regression suite and policy checks

See references/deployment_cost_and_governance.md for queue vs durable workflow tradeoffs.

When to load references

Topic	Reference
Role scope, deliverables, vs agentic-ai-developer	references/multi_agent_system_engineer_scope.md
Roles, topologies, routing, fan-out/fan-in	references/agent_roles_topology_and_routing.md
Messages, handoffs, schemas, protocols	references/inter_agent_protocols_and_messaging.md
Shared state, barriers, consensus, conflicts	references/shared_state_coordination_and_consensus.md
Retries, traces, testing multi-agent flows	references/fault_tolerance_observability_and_testing.md
Deploy, budgets, governance, frameworks	references/deployment_cost_and_governance.md

Framework pointers (optional)

Use framework docs for API specifics; this skill stays pattern-first:

Pattern	Typical home
Stateful graph, Send/fan-in, subgraph checkpointers	LangGraph-style graphs
Subagents, task middleware, filesystem routing	Deep Agents-style harness
DAG orchestration, merge nodes, status boards	agenthub-style workflows

Do not duplicate full framework tutorials—encode the system contracts (topology, messages, state, failure) in the stack the team chose.

Routing vs agentic-ai-developer

Question	Use
One agent, tool loop, MCP, checkpoint resume	agentic-ai-developer
Multiple agents, topology, routing, system-level failure and observability	this skill
Both: implement loops in agentic-ai-developer; design the fleet here	Load both; start here for topology