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Agent Basic

A minimal example of an agent making a single paid API call.

What it does​

  1. Creates a Crumb instance with your private key
  2. Checks the Gateway balance
  3. Makes a single POST /search request to a local provider
  4. Prints the response, amount paid, and transaction hash

Source​

import { Crumb } from 'crumb-alpha-sdk'

const crumb = new Crumb({
  privateKey: process.env.TEST_PRIVATE_KEY!,
  chain: 'arcTestnet',
  onLowBalance: (balance: string) => {
    console.warn(`Low balance warning: ${balance} USDC remaining`)
  },
})

async function main() {
  console.log('Agent address:', crumb.address)
  console.log('Gateway balance:', await crumb.balance(), 'USDC')

  const result = await crumb.fetch('http://localhost:3001/search', {
    method: 'POST',
    body: { query: 'AI research papers 2025' },
    maxPayment: 0.01,
  })

  console.log('Results:', result.data)
  console.log('Paid:', result.formattedAmount, 'USDC')
  console.log('Tx:', result.txHash)
}

main().catch(console.error)

Running​

Requires a provider running on port 3001 (see Provider Express).

# Terminal 1 — start the provider
npx tsx --env-file=.env examples/provider-express/index.ts

# Terminal 2 — run the agent
npx tsx --env-file=.env examples/agent-basic/index.ts

Expected output​

Agent address: 0x22b204CF75B960c6cCf3A49D78a3Aa9845953752
Gateway balance: 9.995 USDC
Results: { results: [...] }
Paid: 0.001 USDC
Tx: 0xabc...