---
title: "A2A vs MCP: Different Layers for Agent Systems"
description: "Understand when Agent2Agent and Model Context Protocol complement each other instead of competing."
language: en
canonical: https://navinresearch.com/blog/agents/a2a-and-mcp.md
topics: ["A2A vs MCP", "Agent2Agent protocol", "Model Context Protocol"]
---

# A2A vs MCP: Different Layers for Agent Systems

Understand when Agent2Agent and Model Context Protocol complement each other instead of competing.

**Short answer:** Use MCP to expose tools, resources, and prompts to an AI application. Use A2A when independently operated agents need to advertise capabilities, exchange task state, and collaborate. A system may use A2A between agents while each agent uses MCP for its local tools.

## Implementation steps

1. Draw the trust boundaries and ownership of every agent and tool server.
2. Use the protocol that matches the boundary instead of wrapping everything in one abstraction.
3. Translate only the minimum task state between A2A and local execution.
4. Apply authentication and authorization independently at both layers.

## Validation checklist

- Trace one task from remote delegation through local tool calls.
- Test capability discovery with unsupported versions.
- Verify that cancellation and errors propagate across both layers.

## Common mistakes

- Calling MCP an agent-to-agent messaging protocol.
- Exposing internal tools directly to remote peers.
- Assuming protocol compatibility creates shared authorization.

## Practical decision

Ship the smallest design that passes the checks above. Record the model, prompt, tool, dataset, and runtime versions used in testing so later changes can be compared rather than guessed. Recheck the linked documentation before relying on provider-specific limits, model names, prices, or preview features; those details change more quickly than the engineering principles in this note.

## Official sources

- [Agent2Agent Protocol documentation](https://a2a-protocol.org/latest/)
- [Model Context Protocol, Introduction](https://modelcontextprotocol.io/docs/getting-started/intro)

---

Reviewed: 2026-08-24. This concise engineering note is educational, not a claim that Navin Research created or independently verified the cited provider technology.