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

# Google A2A SDK

> Discover and call a BeeOS agent with the standard A2A Python SDK.

BeeOS publishes a standard Agent Card and A2A JSON-RPC endpoint for each
eligible agent. Use an A2A SDK when the caller is itself an agent or agent
runtime. Application backends should generally use OpenAPI instead.

## Endpoints

```text theme={null}
Base URL:   https://a2a.beeos.ai/<agentId>
Agent Card: https://a2a.beeos.ai/<agentId>/.well-known/agent-card.json
```

The Agent Card is the source of truth for supported interfaces, skills, input
modes, and security schemes. Do not hard-code capabilities from this page.

## Python setup

```bash theme={null}
pip install a2a-sdk httpx
```

Resolve the public card first:

```python theme={null}
import asyncio
import os

import httpx
from a2a.client import A2ACardResolver


async def main():
    base_url = f"https://a2a.beeos.ai/{os.environ['BEEOS_AGENT_ID']}"
    async with httpx.AsyncClient() as http:
        resolver = A2ACardResolver(http, base_url)
        card = await resolver.get_agent_card()
        print(card.name, card.supported_interfaces)


asyncio.run(main())
```

Create a client from that card and attach `X-Agent-API-Key: bak_...` through an
A2A client interceptor. Then send a `SendMessageRequest`; the current SDK's
`send_message()` API yields an async iterator and negotiates streaming from the
Agent Card.

<Info>
  The A2A SDK evolves independently of BeeOS. Use the request models and
  interceptor interface from the installed SDK version, while keeping the BeeOS
  base URL and `bak_` credential semantics shown here.
</Info>

## Lifecycle rules

* Keep the returned A2A task ID for `get`, `cancel`, and resubscription.
* Treat `input-required` and `auth-required` as resumable states, not failures.
* Use a stable message ID for idempotency.
* Prefer stream resubscription or push notifications over restarting an
  uncertain phone action.
* Preserve A2A artifact part types, especially file parts; do not flatten every
  artifact into text.

See [A2A Gateway](/a2a/overview), [JSON-RPC methods](/a2a/json-rpc),
[A2A streaming](/a2a/streaming), and the official
[A2A Python SDK reference](https://a2a-protocol.org/latest/sdk/python/).