Content
# ADK to A2A Relay
This example is a lightweight relay server that exposes [Agent Development Kit (ADK)](https://google.github.io/adk-docs/) agents as
[Agent2Agent (A2A)](https://a2aproject.github.io/A2A) compliant services.
This library acts as a bridge, allowing any ADK agent to be discovered and communicate within an A2A ecosystem using the standard A2A protocol.
## Features
- Seamless Protocol Bridging: Translates A2A requests into ADK queries and streams ADK responses back as A2A events.
- Dynamic Agent Loading: Run any ADK agent without code modification by simply pointing the CLI to its directory.
- Full Streaming Support: Natively handles the streaming capabilities of both ADK and A2A for real-time, interactive experiences.
- Automatic Type Conversion: Intelligently converts message parts (text, files, data payloads) between A2A and Google GenAI formats.
- Function Call Forwarding: Optionally relays ADK function calls and responses as structured A2A artifacts for advanced tool use cases.
- Artifact Handling: Manages ADK artifacts, making them available within the A2A task context.
- Automatic Agent Card: Generates a standard A2A AgentCard from your ADK agent's metadata, or uses a custom agent.json file if provided.
- Simple CLI Interface: Easy to run from the command line with configurable host, port, and more flags.
## Prerequisites
- Python 3.10+
- [uv](https://github.com/astral-sh/uv)
## Installation
```bash
# Using uv (recommended)
uv venv
source .venv/bin/activate
uv pip install -U -r requirements.txt
```
## Usage
1. Copy `.env-sample` file to the same directory as `.env`.
2. Specify Id of your Google Cloud Project in `GOOGLE_CLOUD_PROJECT` variable.
The project must have Vertex AI APIs enabled.
To run the sample agent:
```bash
python3 -m adk_a2a samples/adk_agents/dice_roll
```
To run your own agent, replace the last argument with your ADK agent's directory.
### CLI Options
`python3 -m adk_a2a [--debug] [--host HOST_NAME] [--port PORT_NUMBER] [--transfer-function-calls] AGENT_DIRECTORY`
You can customize the server's behavior with the following arguments:
| Argument | Description | Default |
| --------------------------- | ------------------------------------------------------------------------ | ----------- |
| `AGENT_DIRECTORY` | (Required) Path to the directory containing the ADK agent. | N/A |
| `--host` | Host address to bind the server to. | `0.0.0.0` |
| `--port` | Port for the HTTP server. | `8080` |
| `--transfer-function-calls` | If set, relays ADK function calls/responses as A2A artifacts. | `False` |
| `--debug` | Enables debug-level logging for detailed output. | `False` |
## Interact with the Agent
Use any A2A-compatible client, such as [A2A Inspector](https://github.com/a2aproject/a2a-inspector).
1. Run the agent server (see above).
2. Connect to `http://127.0.0.1:8080` (if testing locally) or another address you exposed the server with.
3. Make a query to the agent from the client.
## Known limitations
The relay currently doesn't support the following features:
- ADK Long-running tools
- ADK in-task authentication
- Agent-to-agent authentication must be done at the service level when making a request from the client.
## Disclaimer
This is not an officially supported Google product. This project is not eligible for the [Google Open Source Software Vulnerability Rewards Program](https://bughunters.google.com/open-source-security).
Code and data from this repository are intended for demonstration purposes only. It is not intended for use in a production environment.
