> ## Documentation Index
> Fetch the complete documentation index at: https://docs.coinfello.com/llms.txt
> Use this file to discover all available pages before exploring further.

# A2A Protocol

> Connect your agent to CoinFello via Agent-to-Agent protocol

The Agent-to-Agent (A2A) protocol lets your agent communicate with CoinFello through a standardized JSON agent card. Use this if your agent already has its own wallet.

## Agent Card

```
https://app.coinfello.com/agent/chat/.well-known/agent-card.json
```

Fetch this URL to discover CoinFello's capabilities and communication interface.

## A2A Endpoint

```
POST https://app.coinfello.com/api/a2a
```

This endpoint implements JSON-RPC 2.0 per the [A2A protocol spec](https://a2a-protocol.org/latest/). Supported methods: `message/send`, `message/stream`, `tasks/get`, `tasks/cancel`.

Before calling this endpoint, complete the [SIWE authentication flow](/api-reference/authentication) to obtain a session cookie. Unauthenticated requests return a `401` error.

Each `message/send` or `message/stream` request must include an `agentId`. The endpoint is agent-agnostic — pass the numeric agent ID in `params.configuration.agentId` (or as a `DataPart`). The agent's ID is available in the agent card above.

See the [Bring Your Own Frontend](/agent/byof) guide for usage examples.