Agent-to-Agent

Enable secure communication between AI agents using the A2A protocol.

What you’ll build

In this tutorial, you’ll:

1. Run a sample A2A “Hello World” agent
2. Configure Agent Gateway to proxy A2A requests
3. Discover agent skills through the gateway
4. Send tasks to the agent and receive responses

Prerequisites

• uv installed (for running the sample agent)

Overview

This tutorial requires two terminal windows:

┌──────────────┐      ┌──────────────────┐      ┌─────────────────┐
│   Playground │ ──── │  Agent Gateway   │ ──── │  Hello World    │
│   (Browser)  │      │     :3000        │      │  Agent :9999    │
└──────────────┘      └──────────────────┘      └─────────────────┘
                           Terminal 2              Terminal 1

Terminal 1: Start the A2A Agent

Step 1: Clone the sample agents

git clone https://github.com/a2aproject/a2a-samples.git
cd a2a-samples

Step 2: Create environment file (optional)

cat > .env << 'EOF'
# Required for LLM-powered agents (not needed for hello world)
OPENAI_API_KEY=your-openai-key
ANTHROPIC_API_KEY=your-anthropic-key
GOOGLE_API_KEY=your-google-key
EOF

Step 3: Start the Hello World agent

cd samples/python/agents/helloworld
uv run --python 3.12 .

You should see:

INFO:     Uvicorn running on http://0.0.0.0:9999 (Press CTRL+C to quit)

Keep this terminal running and open a new terminal for the next steps.

Terminal 2: Start Agent Gateway

Step 4: Install Agent Gateway

curl -sL https://raw.githubusercontent.com/agentgateway/agentgateway/refs/heads/main/common/scripts/get-agentgateway | bash

Step 5: Create the config

cat > config.yaml << 'EOF'
binds:
- port: 3000
  listeners:
  - routes:
    - policies:
        cors:
          allowOrigins: ["*"]
          allowHeaders: [content-type, cache-control]
        a2a: {}
      backends:
      - host: localhost:9999
EOF

Step 6: Start Agent Gateway

agentgateway -f config.yaml

You should see:

INFO agentgateway: Listening on 0.0.0.0:3000
INFO agentgateway: Admin UI available at http://localhost:15000/ui/

Test in the Playground

Step 7: Open the Playground

Visit http://localhost:15000/ui/playground:

1. Select your A2A route
2. Click Connect to discover the agent’s skills
3. Select the “Returns hello world” skill
4. Type a message and click Send Task

You should see a response:

{"kind":"text","text":"Hello World"}

What’s happening?

• Terminal 1: The Hello World agent runs on port 9999 and handles A2A requests
• Terminal 2: Agent Gateway runs on port 3000 and proxies requests to the agent
• Browser: The Playground UI connects through Agent Gateway to interact with the agent

Agent Gateway provides:

• Automatic agent card URL rewriting to point to the gateway
• Add authentication, rate limiting, and observability transparently
• A unified endpoint for multiple backend agents

Next Steps