# Agent2Agent (A2A) Protocol vs MCP Registry (Official)

Agent2Agent (A2A) Protocol is free, with no paid plan attached. MCP Registry (Official) is free, with no paid plan attached.

| | Agent2Agent (A2A) Protocol | MCP Registry (Official) |
|---|---|---|
| Pricing | Free | Free |
| Free to start | Yes | Yes |
| Category | AI Agents & Automation | AI Agents & Automation |
| Type | MCP Ecosystem | MCP Ecosystem |
| Best for | Open protocol for agents from different vendors to discover and talk to each other | The canonical open-source specification and docs for the Model Context Protocol |

## FAQ

### Agent2Agent (A2A) Protocol vs MCP Registry (Official): what is the difference?

Agent2Agent (A2A) Protocol is free, with no paid plan attached and is listed for open protocol for agents from different vendors to discover and talk to each other. MCP Registry (Official) is free, with no paid plan attached and is listed for the canonical open-source specification and docs for the Model Context Protocol. Both sit in MCP Ecosystem.

### Is Agent2Agent (A2A) Protocol or MCP Registry (Official) cheaper to start with?

Neither — Agent2Agent (A2A) Protocol and MCP Registry (Official) are both free, so the choice comes down to capability rather than cost. Both entries list what they uniquely do above.

### Which should I choose, Agent2Agent (A2A) Protocol or MCP Registry (Official)?

Choose Agent2Agent (A2A) Protocol if you need open protocol for agents from different vendors to discover and talk to each other; choose MCP Registry (Official) if you need the canonical open-source specification and docs for the Model Context Protocol. Flocci AI Tools does not rank one above the other — it shows both feature sets side by side and lets the requirement decide.

## Related

- [Agent2Agent (A2A) Protocol](https://aitools.flocci.in/tool/agent2agent-a2a-protocol)
- [MCP Registry (Official)](https://aitools.flocci.in/tool/mcp-registry-official)
- [Agent2Agent (A2A) Protocol alternatives](https://aitools.flocci.in/alternatives/agent2agent-a2a-protocol)
- [MCP Registry (Official) alternatives](https://aitools.flocci.in/alternatives/mcp-registry-official)
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Source: Flocci AI Tools — https://aitools.flocci.in/compare/agent2agent-a2a-protocol-vs-mcp-registry-official

Facts last verified: October 2026