Does A2A replace MCP?

No. MCP connects an agent to tools and data. A2A lets agents hand work to each other. You can use them together, and neither requires the other.

Can I use MCP and A2A in the same system?

Yes. A2A's own auto repair shop example does. A Manager agent hands work to a Mechanic agent over A2A, and the Mechanic calls diagnostic and repair-manual tools over MCP.

Who governs A2A now that it isn't just a Google project?

A2A is a separate Linux Foundation project with its own governance and Technical Steering Committee. Its governance repository records the current structure.

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MCP vs A2A Explained: Tool Layer vs Agent Collaboration

Published Sep 29, 2026 · Updated Sep 29, 2026 · 5 min read

MCP vs A2A: they solve different problems, so you don't choose between them. MCP (Model Context Protocol) connects an AI agent to tools, data and APIs. A2A (Agent2Agent Protocol) lets separate AI agents talk to each other and hand off work. MCP is agent-to-tool. A2A is agent-to-agent.

The auto repair shop example

A2A's own docs explain the split with a repair shop. A Manager agent talks to the customer. Over A2A, it hands the diagnosis to a Mechanic agent.

The Mechanic then does two different kinds of work:

It calls MCP tools to run diagnostics and search repair manuals. That's an agent using tools, entirely inside its own job.
It asks a Parts Supplier agent, over A2A, whether a part is in stock. That's one agent asking another agent for help, across an organizational boundary.

The pattern holds up. Wherever an agent needs a tool, a document or a database, that's MCP. Wherever it needs another agent's help, that's A2A.

The short version

	MCP	A2A
Connects	An agent to tools and data	One agent to another agent
The question it answers	"How does my agent query this database?"	"How does my agent hand work to an agent I don't control?"
Core pieces	Tools, resources, prompts	Agent Cards, tasks, messages, artifacts
Transport	stdio (local) or Streamable HTTP (remote)	JSON-RPC, gRPC or HTTP+JSON/REST bindings
Governance	MCP's own governance	A separate Linux Foundation project

What MCP covers

MCP describes itself with a USB-C analogy: one standard plug between an AI app and its tools, instead of a custom integration for each pairing. Claude, ChatGPT, VS Code and Cursor all support it.

An MCP server offers tools (actions the AI can call), resources (data it can read) and prompts (reusable templates). Messages are JSON-RPC 2.0. A server can run on your machine over stdio, or remotely over Streamable HTTP.

As of September 2026, the current spec revision is 2026-07-28. It is stateless and requires servers to implement server/discover. MCPifex's gateway uses the handshake-based MCP transport, and clients on the current revision interoperate through the spec's backward-compatibility rules. See instances and tools for how we filter which tools a client sees.

What A2A covers

Google introduced A2A, and it's now a separate Linux Foundation project. Its goal is to let independently built agents work together without exposing how each one works inside.

That's the "Preserve Opacity" principle. Agents swap structured messages, not shared memory or shared tools. One agent asks another to do a job and gets results back, without seeing how the work was done.

An Agent Card describes what an agent can do and how to reach it. A task tracks a piece of work and its state. Artifacts carry the outputs. A2A isn't JSON-RPC only: it also defines gRPC and HTTP+JSON/REST bindings, and a client must use one the server supports.

Do you need both?

Often you need neither at first. If you're connecting one agent to a database or a search tool, MCP is the natural fit. A direct API call or a local library can also do the job. Pick based on which clients need to use it and how much you want to reuse it.

A2A matters when separate agents, maybe built by different teams, need to exchange work and status through a shared contract. Those agents can use MCP, direct APIs or plain code inside. Neither protocol requires the other, and several agents don't automatically mean you need A2A.

Check the handoff and the tools separately

Say a reporting agent asks another team's analyst agent for a weekly summary. The handoff contract covers the period, the output format, status updates and what happens if the analyst needs more input. That's the A2A part.

The analyst then queries a database through MCP, with a read-only role and a small set of enabled tools. That's a separate connection with its own credentials.

A successful handoff doesn't authorize everything downstream. Give the receiving agent only the accounts and tools its task needs. Test both boundaries on their own: a delegation the analyst can't accept, a forbidden database operation, and a tool failure mid-report. Also treat text from a peer agent as untrusted, the same as tool output.

Where MCPifex fits

We host the MCP side. Create an instance of a server such as PostgreSQL, choose which tools are on, and point a client at https://mcpifex.com/mcp with your API key. We don't offer A2A hosting, agent routing or orchestration.

Start with the quickstart or browse the marketplace. For background, read the MCP glossary entry, MCP tools and MCP vs API.

Frequently asked questions

Does A2A replace MCP?: No. MCP connects an agent to tools and data. A2A lets agents hand work to each other. You can use them together, and neither requires the other.
Can I use MCP and A2A in the same system?: Yes. A2A's own auto repair shop example does. A Manager agent hands work to a Mechanic agent over A2A, and the Mechanic calls diagnostic and repair-manual tools over MCP.
Who governs A2A now that it isn't just a Google project?: A2A is a separate Linux Foundation project with its own governance and Technical Steering Committee. Its governance repository records the current structure.