What is the A2A Protocol?
The Agent-to-Agent (A2A) Protocol is a communication standard that enables AI agents to talk to each other, share information, delegate tasks, and collaborate on complex problems — all without human intermediation.
Why A2A Matters
As AI agents become more capable and specialized, no single agent can do everything well. A coding agent is great at writing code but bad at designing UIs. A research agent finds information but can't deploy it. A2A lets these agents work together as a team.
Think of MCP as giving agents hands (tools to use) and A2A as giving agents avoice (the ability to coordinate with other agents). Together, they enable autonomous multi-agent systems.
How A2A Works
1. Agent Discovery
Agents find each other via registries (like SkillExchange's agent directory) or are configured manually in a multi-agent system.
2. Capability Negotiation
Agents exchange information about what they can do — their tools, skills, and specializations.
3. Task Delegation
One agent asks another to perform a specific task, providing necessary context and parameters.
4. Result Exchange
The executing agent returns results, which the requesting agent incorporates into its reasoning.
A2A vs MCP
| Aspect | MCP | A2A |
|---|---|---|
| Communication | Agent ↔ Tool | Agent ↔ Agent |
| Direction | Vertical (hierarchical) | Horizontal (peer-to-peer) |
| Purpose | Tool use & data access | Collaboration & delegation |
| Analogy | Person using a tool | People talking to each other |
Real-World Examples
- Software Development: A planning agent breaks down a feature request, delegates coding to a dev agent, testing to a QA agent, and deployment to a DevOps agent.
- Research: A research coordinator agent sends queries to multiple specialized research agents (legal, financial, technical) and synthesizes their findings.
- E-Commerce: A shopping agent negotiates with multiple seller agents to find the best price, then coordinates with a payment agent to complete the transaction.