Agent-to-Agent Communication (A2A)
Agent-to-Agent Communication (A2A) explained
A research agent needs another service to perform a bounded subtask. Both sides must understand the request, required information and task state. A2A can provide a common communication format for that exchange.
The benefit concerns communication across systems, not automatically better decisions. An advertised capability must actually exist. A successfully delivered result can still be incomplete or incorrect. The task and its acceptance criteria therefore remain important.
MCP and A2A have different emphases: MCP connects AI applications with tools and data; A2A focuses on communication between agents. Both can belong in one solution. Choosing a protocol does not replace architectural decisions or permission to exchange data.
Plan handovers around the task. Who owns the complete outcome, how are clarifications requested and what happens after cancellation or repetition? Information should not be shared merely because another agent is technically reachable.
Examples
Hypothetical application
An assistant preparing a research brief delegates a limited source question to a specialist service. They exchange task status and results. The original assistant checks the references and identifies unresolved questions before the team uses the draft.
Key Points
- A2A is a specific protocol, not every multi-agent arrangement.
- Distinguish reachability, capability and permission.
- Successful exchange does not establish subject-matter quality.
- Assign ownership of the overall result and failure handling.
Practical application
Describe a specific handover with permitted data, expected results and responsibility. Check the capabilities supported by both sides. Test clarification, incomplete responses, cancellation and duplicate requests as well as the successful normal case.
Useful measures
Successful handovers
Tasks with a fully received and professionally accepted result.
Failure handling
Visibility and controlled handling of cancellations, questions and repetitions.
Coordination effort
Additional exchange time and cost relative to the benefit of dividing the work.
Common mistakes
- Presenting a protocol as a guarantee of independent, error-free collaboration.
- Accepting a service’s capability description without verification.
- Passing more data or permissions than the delegated task requires.
Sources and context
- A2A Protocol: What is A2A?
Official context on the Agent2Agent protocol and its relationship to MCP.
Frequently Asked Questions about Agent-to-Agent Communication (A2A)
No. Agents within one application can collaborate through other internal mechanisms. A2A is one possible integration approach when separate agent systems need a common way to exchange tasks and information.
No. They have different emphases and can complement each other. Assess whether the task requires access to a tool, delegation to another agent or both.
The application must establish that. Technical delegation does not automatically transfer professional responsibility or grant additional access. The requesting system needs a verifiable return path and clear acceptance criteria.
Related links
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