# A2A agents

> An A2A v1.0 agent published behind Flexway is called at the gateway's address, in JSON-RPC or HTTP+JSON. Product side: Agents: MCP and A2A; operations side…

Guide - Since version 1.2.0 - Flexway v1.6.3 - https://flexway.io/en/docs/developer-a2a/

> An A2A v1.0 agent published behind Flexway is called at the gateway's address, in JSON-RPC or HTTP+JSON.
>
> Product side: [Agents: MCP and A2A](https://flexway.io/en/docs/product-agents/); operations side: [A2A agents](https://flexway.io/en/docs/operations-a2a/).

## Finding the agent

```bash
curl https://api.example.com/agents/support/.well-known/agent-card.json
```

The card is public, served with an `ETag`; its `supportedInterfaces` give the gateway's addresses. It
is not signed yet.

## Calling

```bash
curl -s https://api.example.com/agents/support -H "Authorization: Bearer $TOKEN" \
  -H 'Content-Type: application/json' -H 'A2A-Version: 1.0' \
  -d '{"jsonrpc":"2.0","id":1,"method":"SendMessage","params":{"message":{"role":"ROLE_USER","messageId":"m-1","parts":[{"text":"Where is my order 42?"}]}}}'
```

| Rule | Detail |
| --- | --- |
| Identity | Those the card declares (usually an OIDC token); the called agent receives a token exchanged for it, never yours |
| Quota | Writing (`SendMessage`...) counts; reading a task (`GetTask`) is free |
| Streams | `SendStreamingMessage` and `SubscribeToTask` are capped per caller and last at most the operator's limit: follow a longer task with `GetTask` |
| Tasks | Bound to your identity by the agent: another caller gets "task not found" |
| Push notifications | Only toward the `https` hosts the operator allows |