Agent-to-Agent

Enable secure communication between AI agents using the A2A protocol.

What you’ll build

In this tutorial, you configure the following.

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

Before you begin

• uv installed (for running the sample agent)

Overview

This tutorial requires two terminal windows:

┌──────────────┐      ┌──────────────────┐      ┌─────────────────┐
│   Playground │ ──── │  agentgateway   │ ──── │  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 .

Example output:

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 agentgateway

Step 4: Install agentgateway

curl -sL https://agentgateway.dev/install | bash

Step 5: Create the config

cat > config.yaml << 'EOF'
# yaml-language-server: $schema=https://agentgateway.dev/schema/config
binds:
- port: 3000
  listeners:
  - routes:
    - policies:
        cors:
          allowOrigins: ["*"]
          allowHeaders: [content-type, cache-control]
        a2a: {}
      backends:
      - host: localhost:9999
EOF

Step 6: Start agentgateway

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

Example output:

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

What’s happening?

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

Agentgateway 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