---
title: Agent-to-Agent (A2A) server
description: The Agent-to-Agent (A2A) server enables external A2A clients to communicate with Elastic Agent Builder agents. Returns metadata for a specific agent...
url: https://www.elastic.co/elastic/docs-builder/docs/2395/solutions/search/agent-builder/a2a-server
---

# Agent-to-Agent (A2A) server
The [**Agent-to-Agent (A2A) server**](https://github.com/a2aproject/A2A) enables external A2A clients to communicate with Elastic Agent Builder agents.

## Agent cards endpoint

Returns metadata for a specific agent. The `agentId` is a path parameter that corresponds to your agent IDs:
```
GET /api/agent_builder/a2a/{agentId}.json
```


## A2A protocol endpoint

Interact with agents following the A2A protocol specification:
```
POST /api/agent_builder/a2a/{agentId}
```

<important>
  Both A2A endpoints require API key authentication. For more information about the A2A protocol, refer to the [A2A protocol specification](https://a2aprotocol.ai/docs/guide/a2a-protocol-specification-python#protocol-flow-diagram).
</important>