Agent-to-Agent Protocol
Quick Take
- In brief: A2A lets separate agent systems exchange tasks and results.
- Useful for: Handing work between products or teams that use different agent frameworks.
- Main limit: A shared protocol does not make an agent trustworthy or correct.
Overview
A support agent may ask an order-system agent to investigate a refund. A2A gives the two systems a common way to describe capabilities, send work, and return results.
Core Definition
A2A is an open protocol for independent agent systems to discover capabilities, exchange messages, and collaborate on tasks.
Background and Evolution
A2A addresses a practical problem: organizations often build agents with different frameworks and cannot share internal state. Version 1.0.0 defines a stable protocol contract; implementations can still differ in transport and deployment.
How It Works
A client discovers an agent’s description, checks whether it supports the needed task, then sends a message or task request. The remote agent can return a result or report task progress before it finishes.
Applications in Software Development and Testing
A development assistant can delegate a dependency audit to a security agent, then receive findings as a separate result. The caller should retain the links between the request, the agent, and the returned evidence.
Strengths and Limitations
A shared contract can reduce custom integrations across frameworks. It does not define an organization’s trust policy, guarantee compatible business meanings, or verify the returned work.
Comparison with Similar Terms
MCP commonly connects a model application to tools and data. Multi-agent orchestration describes how a system assigns and coordinates work. A2A describes messages between independent agents.
Best Practices
Pin the protocol version, authenticate each remote service, limit shared data, and validate results before using them in another workflow.
Common Pitfalls
Do not treat protocol compatibility as authorization. A technically valid call can still send sensitive data to the wrong agent or trigger an unsafe action.
FAQ
Does A2A make a remote agent trustworthy?
No. Callers must check the agent’s identity, permissions, and output.