MCP is a toolbox. A2A is a coworker.
MCP and A2A get lumped together, but they solve different problems.
Something I've been chewing on: MCP and A2A get lumped together, but they solve different problems.
MCP exposes tools, resources, and prompts to an AI client. It gives an agent capabilities like search_notes, read_note, or create_note_pr.
A2A is also a protocol, but designed for one agent to delegate work to another. Instead of calling a low-level tool, the caller asks a publishing agent to "turn this idea into a note and open a PR." The publishing agent owns the workflow and decides how to do it.
The mental model I keep landing on:
- MCP is a toolbox.
- A2A is a coworker.
They're complementary. An A2A agent can use MCP tools internally.
Example flow: ChatGPT → A2A publishing agent → MCP tools (GitHub, Vercel, and so on).
MCP is the plumbing. A2A is the collaboration layer.