What is an A2A Agent Card?
Complete Guide

A2A (Agent-to-Agent) Protocol is an open standard that enables interoperability between AI agents. The Agent Card is the core concept of this protocol — a standardized JSON document that describes an agent's capabilities, interfaces, and metadata.

It serves as the primary information source for other AI agents to discover your agent, understand its capabilities, and delegate tasks to it.

Agent Card Structure

An Agent Card is a JSON document with the following structure. Each field falls into two categories: basic agent information and a list of operable skills.

{
  "name": "email_agent",
  "version": "1.0.0",
  "description": "Agent that handles email operations",
  "provider": {
    "organization": "Example Corp"
  },
  "supportedInterfaces": [...],
  "capabilities": { "streaming": true },
  "defaultInputModes": ["text/plain"],
  "defaultOutputModes": ["text/plain"],
  "skills": [...]
}

Deployment

Publish your Agent Card at /.well-known/agent-card.json on your web server.

1. Create your Agent Card with the Generator and download the JSON file
2. Place agent-card.json in the /.well-known/ directory
3. Configure your server to serve it with Content-Type: application/json

A2A vs MCP Comparison

MCP (Model Context Protocol) is Anthropic's protocol focused on connecting LLMs with tools and data sources. A2A focuses on peer-to-peer collaboration between agents.

The two protocols are complementary, and the community continues to refine the specifications.