What Agent-to-Agent Communication Means
Agent-to-agent communication happens when one AI agent needs another independent agent to do part of a job.
The first agent does not need access to the second agent's private memory or code. It needs a clear description of the other agent's skills, a secure way to send a message, and a shared way to track the work.
That is the problem the open Agent2Agent protocol is designed to solve.
A Four-Step Agent Handoff
Imagine a planning agent that needs current shipping rates from a specialist logistics agent. The work can move through four visible stages.
- Discover the agent The planning agent reads an Agent Card that describes the logistics agent and its supported skills.
- Send the request It sends a message with the destination, package facts, and expected result.
- Track the task The logistics agent can return status updates while it checks the current rates.
- Receive the artifact The finished rate comparison returns as structured work the planning agent can use.
A2A, MCP, and APIs Do Different Jobs
These technologies can work together. They should not be collapsed into one vague idea about agents talking.
| Method | Connects | Main job | Example |
|---|---|---|---|
| Agent2Agent protocol | Independent agents | Discovery plus messages and task coordination | A planning agent delegates shipping research |
| Model Context Protocol | An AI application and tools or resources | Tool discovery and controlled access | An agent reads a database through an MCP server |
| Direct API | Two known software systems | A defined request and response | An agent requests a current inventory count |
What a Website Needs Before It Becomes an Agent Source
Most websites are information sources rather than independent agents. They do not need an Agent Card just because AI crawlers visit them.
A useful website starts with clear pages, stable URLs, accurate schema, and current data endpoints. Those pieces help an agent retrieve information without pretending the site can accept or complete a delegated task.
An Agent2Agent endpoint makes sense when the service can really accept a message, manage a task, enforce authentication, and return a defined result.
What Makes an Agent Handoff Trustworthy
The protocol carries the exchange. The service still has to protect the work and return dependable results.
- A capability description that matches what the agent can actually do
- Authentication and authorization for protected tasks
- Clear input and output formats
- Status and error states the calling agent can understand
- Source facts that remain current throughout the task