A2A vs MCP: what's the difference.
Short version: MCP connects one agent to its tools; A2A connects agents to each other. They're not competitors — they solve different layers, and a serious system uses both. Here's the clean mental model, dimension by dimension, plus where each protocol fits.
MCP = agent-to-tool · A2A = agent-to-agent
They sound similar, so people assume you pick one. You don't.
A2A and MCP both showed up in the agent conversation at roughly the same time, both are protocols, and both involve agents — so the internet keeps framing them as rivals and asking which one 'wins.' That framing is the confusion. They operate at different layers and answer different questions, and treating them as an either/or leads to systems that are missing half the picture.
One model: MCP gives an agent capabilities, A2A lets agents combine them.
Keep the layers straight and the confusion evaporates. MCP is how an agent reaches its tools and data. A2A is how agents reach each other. Everything else follows from that split.
MCP: tools for one agent
The Model Context Protocol (MCP) is how a single agent connects to the tools, data, and context it needs to do its job — a filesystem, a database, an API, a search index. It's the agent-to-tool layer.
A2A: agents talking to agents
The Agent2Agent protocol (A2A) is how one agent discovers and delegates work to another agent over HTTP. It's the agent-to-agent layer — coordination between independent, potentially multi-vendor agents.
Different layers, not competitors
A2A and MCP don't overlap or compete. MCP gives an agent its capabilities; A2A lets agents combine those capabilities across the network. Framing them as rivals is the core misconception.
You usually need both
A realistic system uses MCP so each agent can reach its tools, and A2A so agents can hand tasks to one another. Pick one and you either have a capable loner or a coordinator with nothing to coordinate.
The client relationship differs
In MCP, an agent acts as a client to tool servers. In A2A, an agent is a peer to other agents — it can be both caller and callee. The trust and identity model is agent-to-agent, not agent-to-tool.
a2a cloud does both, natively
Deploy once and your agent is A2A-reachable with a valid agent card and also exposes every skill as an MCP tool. You don't choose between the protocols — you get both from a single deploy.
MCP vs A2A, dimension by dimension.
Frequently asked.
What is the difference between A2A and MCP?
MCP (Model Context Protocol) connects a single agent to its tools and data sources — it's the agent-to-tool layer. A2A (Agent2Agent) connects agents to each other so they can discover and delegate tasks — it's the agent-to-agent layer. They operate at different layers and are complementary rather than competing.
Is A2A a replacement for MCP?
No. A2A does not replace MCP and MCP does not replace A2A. MCP gives an agent access to tools and context; A2A lets agents coordinate with each other. A complete system typically uses both — MCP so each agent can act, A2A so agents can collaborate.
Do I need both A2A and MCP?
Usually, yes. If your agent needs to call tools, read data, or use context, you want MCP. If your agents need to delegate work to one another or interoperate across frameworks and vendors, you want A2A. Most real deployments involve both, which is why a2a cloud supports each natively.
When should I use A2A instead of MCP?
Use MCP when the problem is giving one agent a capability — connecting it to an API, a database, or a filesystem. Use A2A when the problem is coordination — one agent needs another agent to handle part of a task. They address different problems, so the choice is usually 'both,' scoped to where each fits.
Does a2a cloud support MCP and A2A together?
Yes. Every agent you deploy on a2a cloud is A2A-native — it serves a valid agent card and A2A endpoints — and every one of its skills is simultaneously exposed as an MCP tool. You get both protocols from a single deploy, with scoped grants and a signed receipt for every run.
Related guides.
All guides live in the guides index.
Get both from one deploy.
You don't have to pick a protocol. Deploy any agent — LangGraph, OpenAI Agents SDK, CrewAI, or custom — to a2a cloud and it's A2A-native with a valid agent card and A2A endpoints, while every skill it exposes is simultaneously an MCP tool. Managed Postgres, scoped grants, and a signed receipt for every run come standard. One deploy, both layers, no false choice.