A2A Payments (APay)

Blockchain-native USDC payments for AI agents on Base chain. Pay for services, manage budgets, and handle micropayments.

Quick Start

Check your balance:

Use apay_check_balance to see my USDC balance

Pay a service:

Use apay_pay_service with serviceId "svc-123" and amount "0.50"

Available Tools

Balance & Budget

Tool	Description
apay_check_balance	Check USDC balance, daily budget, spending limits
apay_budget_check	Verify if a specific amount is affordable
apay_spending_history	Get spending analytics and history

Payments

Tool	Description
apay_pay_service	Pay a service (agent pays gas)
apay_pay_signed	Gasless signed payment (server submits on-chain)
apay_estimate_cost	Estimate cost including 0.5% platform fee

Services

Tool	Description
apay_list_services	List available APay services
apay_get_service	Get detailed service info

Payment Channels (Streaming)

Tool	Description
apay_channel_status	Check channel status
apay_stream_open	Open channel with USDC deposit
apay_stream_pay	Sign off-chain micropayment
apay_stream_close	Close channel (refund unspent)

x402 Protocol

Tool	Description
apay_x402_fetch	Fetch URL with automatic x402 payment on HTTP 402

Workflows

Pay for a tool execution

1. apay_budget_check — verify affordability
2. apay_estimate_cost — see total with fees
3. apay_pay_service — execute payment
4. Receive payment receipt with tx hash

Streaming micropayments

For services that charge per-request (API calls, data feeds):

1. apay_stream_open — deposit USDC into channel
2. apay_stream_pay — sign micropayments (off-chain, instant)
3. apay_stream_close — settle on-chain, refund remainder

x402 auto-payment

For services using the HTTP 402 payment protocol:

Use apay_x402_fetch with url "https://api.example.com/premium/data" and maxPayment "1.00"

The tool automatically detects 402 responses, pays the required amount, and retries the request.

Network

• Chain: Base (Coinbase L2)
• Stablecoin: USDC (6 decimals)
• Model: Escrow-based sessions with spending limits
• Testnet: base-sepolia for development