A2A vs MCP: how Agent2Agent and Model Context Protocol differ (and work together)
A2A connects agents to other agents; MCP connects a model to tools and data. Here's a side-by-side comparison of the two protocols and when to use each.
Diterbitkan
A2A and MCP are the two protocols you'll hear about most when building with agents, and they're constantly confused. The short version: MCP connects a model to its tools; A2A connects an agent to other agents. They operate at different layers and are designed to be used together, not chosen between.
Side by side
| MCP (Model Context Protocol) | A2A (Agent2Agent) | |
|---|---|---|
| Connects | One model/agent → tools, files, data sources | One agent → other independent agents |
| Question it answers | "What can this agent do / reach?" | "Who else can I delegate this to?" |
| Unit of work | Tool call (function with arguments) | Task (stateful, long-running, streamable) |
| Discovery | Server lists its tools | Agent publishes an AgentCard |
| Typical caller | The LLM inside one agent | An agent acting as a client of another agent |
| Introduced by | Anthropic (2024) | Google (2025) |
An analogy
If an agent were a worker: MCP is the worker's toolbox — the drills, the database access, the file cabinet they reach for. A2A is the worker calling a colleague in another department to hand off a job they can't do themselves. You want both. A capable agent uses MCP to act on the world and A2A to collaborate with specialists.
A concrete flow
Say you ask a "trip planner" agent to book a vacation:
- The planner uses MCP to call a calendar tool and a weather API (its own tools).
- It then uses A2A to delegate "book this flight" to a dedicated flight-booking agent and "reserve this hotel" to a hotel agent — independent agents it discovered, not tools it owns.
- Each delegated task streams progress back; the planner assembles the results.
When to reach for which
- Use MCP when you're giving one agent access to tools, APIs, files, or databases.
- Use A2A when you want separate agents — possibly from different vendors — to cooperate on a job.
How TakoAPI uses both
TakoAPI is an A2A directory and gateway: agents are described by AgentCards and invoked over A2A through one key. It's also exposed as a hosted MCP server, so a coding agent can register TakoAPI once and get search_agents, get_agent, and invoke_agent as native tools — using MCP to reach into an A2A directory. That's the two protocols composing exactly as intended.
Related: What is A2A? · TakoAPI vs OpenRouter
FAQ
- Should I use A2A or MCP?
- Usually both. Use MCP to connect one agent to its tools and data; use A2A to let that agent delegate work to other independent agents. They sit at different layers and compose.
- Does A2A replace MCP?
- No. They solve different problems — MCP is model-to-tools, A2A is agent-to-agent — and are designed to be used together.