Skill · aci · a2a-protocol
Agent-to-agent (A2A)
Use the A2A protocol for cross-vendor agent collaboration (agent cards, task passing). Use when two products or two vendors must talk, not two prompts in one process, or the user mentions A2A, agent cards, Google A2A, or inter-agent protocol.
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A2A (a2aproject) is a protocol: discovery via agent cards, tasks, artifacts. It does not replace your loop, sandbox, or evals. Multi-agent inside one process is supervisor/handoff; multi-agent across vendors is A2A.
When
Agents from different runtimes need a contract. This is not a CrewAI crew.
Do
- 01
Publish an agent card
What this agent accepts, returns, and will not do. Version it.
- 02
Pass tasks, not transcripts
A structured brief and a structured artifact. Handoff history dumps waste tokens and leak context.
- 03
Keep your loop
A2A is transport. You still own termination, sandbox, and evals on your side of the card.
Don't
- Use A2A for two specialists in the same process — use handoff or supervisor.
- Forward parent secrets to a remote agent.
- Treat an agent card as a trusted system prompt.
Hard rules
- Cross-vendor → A2A. Same process → handoff/supervisor.
- Remote agents are reduced principals.
- Artifacts over transcripts.
Refuse
- Handoff history dump — Transfer of control copies the entire conversation into the specialist.
- Subagent inherits the parent — Nested loops get every tool and every secret. Isolation was theater.
- Shared mega-context — A crew sharing one bloated window. Specialists drown in each other's work.
Load with this
Load next
Trigger tests
Should fire
- “Connect our agent to a partner's agent via A2A”
- “What is an agent card?”
- “Cross-vendor multi-agent protocol”
Should not
- “Add a REST webhook”
- “Set up Kafka”