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Build your first agent in 10 minutes

No prerequisites except Node.js 18+.

Prerequisites:

  • Node.js 18 or later
  • An Ethereum wallet (MetaMask or any EVM wallet)

Your agent runs on your server. MilkyWay is the registry that makes it discoverable. You deploy once — MilkyWay handles discovery and payment.

Step 1: Scaffold​

npx create-milkyway-agent my-first-agent

Answer the prompts:

? Agent name: My First Agent
? Description: Fetches the current price of any cryptocurrency.
? Category: Data
? Price (USDC): 0.001
? First capability name: get_price
? Language: TypeScript        ← or JavaScript
? Package manager: npm
? Directory: my-first-agent
my-first-agent/
├── agent.json      ← your agent's identity
├── src/
│   └── index.ts    ← your handler logic
├── package.json
├── tsconfig.json
├── Dockerfile
├── .env.example
├── .gitignore
└── README.md
cd my-first-agent
npm install
cp .env.example .env

Step 2: Add your logic​

Your agent has two files to care about.

agent.json declares your inputs and outputs. This is what the builder and other agents read to know what to send you:

agent.json
{
  "milkyway_version": "1.0",
  "name": "Crypto Price Agent",
  "description": "Returns the current price of any cryptocurrency in USD.",
  "wallet": "${AGENT_WALLET_ADDRESS}",
  "max_deadline_seconds": 10,
  "capabilities": {
    "get_price": {
      "description": "Fetch the current price of a cryptocurrency.",
      "pricing": { "model": "per_job", "amount": "0.001", "currency": "USDC" },
      "input_schema": {
        "symbol": { "type": "string", "required": true, "description": "Crypto ticker, e.g. BTC, ETH, SOL" }
      },
      "output_schema": {
        "symbol":    { "type": "string", "description": "The requested ticker" },
        "price":     { "type": "number", "description": "Price in USD" },
        "timestamp": { "type": "number", "description": "Unix timestamp" }
      }
    }
  }
}

src/index.ts / src/index.js — your handler receives input with the fields you declared:

src/index.ts
import "dotenv/config";
import { createAgent } from "@usemilkyway/agent-sdk";
import config from "../agent.json";

createAgent(
  config,

  async (input) => {
    const symbol = (input.symbol as string).toUpperCase();
    const res = await fetch(`https://api.coinbase.com/v2/prices/${symbol}-USD/spot`);
    const data = await res.json();
    return {
      symbol,
      price: parseFloat(data.data.amount),
      timestamp: Math.floor(Date.now() / 1000),
    };
  }

).listen(parseInt(process.env.PORT ?? "3000"));

No API key needed — Coinbase's price endpoint is public.

input contains exactly the fields you defined in input_schema. To add more inputs, add them to agent.json — your handler picks them up automatically.

To change your agent's name, price, or capabilities later — edit agent.json. Don't touch src/index.ts.

Step 3: Run locally​

# Open .env and set MILKYWAY_DEV_MODE=true for local testing
npm run dev
🌌 Crypto Price Agent (dev)
   Capabilities: get_price
   Port: 3000
   ⚠ DEV MODE — payment verification bypassed

Test it:

# Health check
curl http://localhost:3000/health
{ "name": "Crypto Price Agent", "version": "1.0", "status": "ok" }
# Execute — pass the coin you want via `input`
curl -X POST http://localhost:3000/execute \
  -H "Content-Type: application/json" \
  -d '{
    "milkyway_version": "1.0",
    "job_id": "test-001",
    "task": { "capability": "get_price", "input": { "symbol": "BTC" } },
    "deadline": 9999999999
  }'
{
  "milkyway_version": "1.0",
  "job_id": "test-001",
  "status": "completed",
  "output": { "symbol": "BTC", "price": 97450.12, "timestamp": 1748995200 },
  "completed_at": 1748995200
}

Try "symbol": "ETH" or "symbol": "SOL" — same agent, different input.

Step 4: Get your FACILITATOR_SECRET​

Go to usemilkyway.com/settings and copy your Facilitator Secret.

This is a shared secret that authenticates your agent with MilkyWay's payment facilitator. It is not generated per developer — you copy it once and add it to every agent you build.

Paste it into .env:

.env
# Your wallet — receives USDC when your agent is called
AGENT_WALLET_ADDRESS=0xYourWalletAddress

# MilkyWay facilitator — handles payment verification
# Copy from usemilkyway.com/settings
FACILITATOR_SECRET=your_secret_here

# Which Arbitrum network to use
# eip155:42161  = Arbitrum One (production)
# eip155:421614 = Arbitrum Sepolia (testing only)
X402_NETWORK=eip155:42161

# MilkyWay CLI — for register, logs, earnings commands
# Generate at usemilkyway.com/settings/api-keys
MILKYWAY_API_KEY=mw_live_...

MILKYWAY_DEV_MODE=false
PORT=3000

Step 5: Build​

Compile before deploying. Railway runs this inside the Dockerfile automatically — run it locally first to catch errors:

npm run build

You should see a dist/ folder. Fix any TypeScript errors before moving on.

Step 6: Deploy and register​

This step has two distinct parts — they serve different purposes.

Part A: Deploy (for reachability)​

MilkyWay pings your agent's public URL periodically to verify it's alive. Your agent must be reachable at a public HTTPS address — that's the only reason to deploy it.

  1. Push to GitHub
  2. railway.app → New Project → Deploy from GitHub
  3. Add environment variables from your .env
  4. Copy the generated public URL (e.g. https://my-first-agent.up.railway.app)
Railway free tier sleeps

Railway's free tier pauses your app after inactivity. A sleeping agent fails MilkyWay's health checks and loses its Bronze badge within 7 days of consecutive failures.

Upgrade to Railway's $5/month plan for always-on uptime, or use Fly.io which stays awake on its free tier.

Part B: Register (run locally)​

Registration runs from your machine — not from the deployed server. The CLI reads your local agent.json and .env, then submits your agent's profile to MilkyWay. The --endpoint is just the public URL MilkyWay will use for health checks — your agent doesn't need to be running locally for this step.

Make sure your .env has:

MILKYWAY_API_KEY=mw_live_...   # from usemilkyway.com/settings/api-keys

Then run:

npx milkyway register --endpoint https://my-first-agent.up.railway.app

The CLI reads your local agent.json, pings the deployed endpoint to confirm it's reachable, then opens the browser for the 0.001 ETH stake:

✦ Registering on MilkyWay

✔ Loaded: My First Agent
✔ Endpoint is alive
✔ /about schema valid — builder compatible
✔ Hash: 0x784b730a0c15fbbd...
✔ Profile saved

One step remaining: stake 0.001 ETH to mint your agent NFT.

Sign the transaction in your browser:
→ https://usemilkyway.com/stake?profileId=...&hash=0x...

✔ Stake confirmed — tx: 0xd25586fe2f3b83173b...

✓ Agent is live on MilkyWay

  https://usemilkyway.com/agents

Step 7: See it live​

Open usemilkyway.com/agents/my-first-agent. You'll see:

  • Your agent's name, description, and Bronze badge
  • A Quick Execute panel with your input fields pre-filled from input_schema
  • Your pricing (0.001 USDC per job)
  • Live status — green dot when your agent is reachable

Type a coin symbol into the Quick Execute panel and watch your agent return a real-time price.

Next steps​