---
title: A2A Agent Card Validator
description: Validate your A2A Agent Card against the Agent-to-Agent protocol (a2a.proto v1.0.0). Confirm agents can discover your server at /.well-known/agent-card.json.
last_updated: 2026-05-11
canonical_url: https://agent-ready.dev/agent-card-validator
---

# A2A Agent Card Validator

> Validate your A2A Agent Card against the Agent-to-Agent protocol (a2a.proto v1.0.0). Confirm agents can discover your server at `/.well-known/agent-card.json`.

## What is an A2A agent card?

A JSON document published at `/.well-known/agent-card.json` that declares an agent's name, version, supported interfaces, input/output modalities, and callable skills. Lets other agents (travel planners, orchestrators, concierges) discover what your agent can do and how to call it.

## Why should I publish an A2A agent card?

A2A is the open protocol for agent-to-agent communication. If your software is itself an agent — runs an LLM, makes decisions, takes actions — publishing an agent card lets other agents invoke or compose with yours over a portable interface (JSON-RPC, gRPC, or HTTP+JSON). Spec ratified as a2a.proto v1.0.0.

## What does the A2A agent card validator check?

Per a2a.proto v1.0.0, eight top-level fields are required:

- `name`
- `description`
- `version`
- `capabilities`
- `supportedInterfaces`
- `defaultInputModes`
- `defaultOutputModes`
- `skills`

Each `supportedInterfaces` entry also needs `url`, `protocolBinding` (JSONRPC, GRPC, or HTTP+JSON), and `protocolVersion`. Empty arrays and objects are allowed but the fields must exist. `Content-Type: application/a2a+json` is preferred; `application/json` is also accepted. The `/.well-known/` path is reserved by RFC 8615 for machine-readable discovery.

## Minimal valid example

```json
{
  "name": "acme-trip-planner",
  "description": "Plans multi-leg international travel.",
  "version": "1.0.0",
  "capabilities": {},
  "supportedInterfaces": [
    {
      "url": "https://agents.acme.dev/a2a",
      "protocolBinding": "JSONRPC",
      "protocolVersion": "1.0.0"
    }
  ],
  "defaultInputModes": ["text/plain"],
  "defaultOutputModes": ["text/plain"],
  "skills": []
}
```

## Specifications

- [A2A Protocol](https://a2a-protocol.org)
- [A2A spec on GitHub](https://github.com/a2aproject/A2A/blob/main/docs/specification.md)
- [RFC 8615 — Well-Known URIs](https://datatracker.ietf.org/doc/html/rfc8615)

---

Validate your A2A agent card: <https://agent-ready.dev/agent-card-validator>

Related guide: [MCP vs A2A vs agents.json](https://agent-ready.dev/mcp-vs-a2a-vs-agents-json)

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