tools402 × Google AP2

Google's Agent Payments Protocol (AP2) landed in September 2025 with 60 launch partners. tools402 is natively compatible — four touchpoints, no shim required. This page documents how the pieces line up.

TL;DR. AP2 is a payment-protocol-agnostic layer that lets a user issue a signed Intent Mandate to an AI agent, which the agent then redeems with a merchant. tools402 acts as both the merchant (the API marketplace) and an optional identity facilitator: we accept any AP2 Intent Mandate via the standard X-AP2-Mandate-Accepted response header and, for agents that don't have one yet, we offer a native EIP-712 builder at /v1/agent/identity.

The four touchpoints

Touchpoint 1

HTTP 402 quote

Every paid endpoint returns a deterministic 402 Payment Required body with accepts array, atomic price, USDC asset, and recipient wallet — the universal contract AP2 agents read before paying.

Touchpoint 2

Mandate-aware settlement

The x402 middleware tags every successful settlement with X-AP2-Mandate-Accepted: transfer-with-authorization, signalling that an EIP-3009 gasless mandate is valid as the payment vehicle.

Touchpoint 3

Audit trail

GET /v1/_audit/<txHash> returns the on-chain settlement proof for any paid call, satisfying the AP2 requirement that every Intent Mandate redemption be independently verifiable.

Touchpoint 4

Native Intent Mandate builder

POST /v1/agent/identity builds and verifies canonical EIP-712 typed data for an AP2 IntentMandate — for agents without an existing AP2 SDK. $0.001/call.

What is an Intent Mandate?

An Intent Mandate is a structured, user-signed message that authorizes an AI agent to spend up to a fixed amount of USDC for a specific intent within a time window. It's the AP2 equivalent of a one-shot prepaid card with policy rules baked in.

tools402's native canonical form (EIP-712, chain id 8453 = Base mainnet):

{
  domain: {
    name: "tools402-ap2",
    version: "1",
    chainId: 8453,
    verifyingContract: "0x0000000000000000000000000000000000000000"
  },
  types: {
    IntentMandate: [
      { name: "agent",            type: "address" },
      { name: "description",      type: "string"  },
      { name: "max_spend_atomic", type: "uint256" },
      { name: "expires_at",       type: "uint256" },
      { name: "nonce",            type: "bytes32" }
    ]
  },
  primaryType: "IntentMandate",
  message: {
    agent:            "0xAGENT_WALLET",
    description:      "Summarise the latest 3 arXiv quantum papers",
    max_spend_atomic: "50000",
    expires_at:       1740960000,
    nonce:            "0x…32 bytes…"
  }
}

Build a mandate

curl -X POST https://api.tools402.dev/v1/agent/identity \
  -H "X-Payment: <EIP-3009 session token>" \
  -H "Content-Type: application/json" \
  -d '{
    "action": "build",
    "agent_wallet":      "0xAGENT_WALLET",
    "intent_description":"Summarise latest 3 arXiv quantum papers",
    "max_spend_atomic":  50000,
    "expires_at":        1740960000
  }'

Verify a signature

curl -X POST https://api.tools402.dev/v1/agent/identity \
  -H "X-Payment: <EIP-3009 session token>" \
  -H "Content-Type: application/json" \
  -d '{
    "action":     "verify",
    "typed_data": { … },
    "signature":  "0x…65 bytes…"
  }'

# → { valid: true, recovered_address: "0xAGENT_WALLET", expired: false }

Why USDC on Base?

AP2 is payment-rail agnostic — credit card, bank transfer, stablecoin. tools402 chose USDC on Base (Coinbase's L2) for three reasons:

Atomic-grain pricing. Tools cost $0.0001 to $0.250. Cards can't price below ~$0.30 without eating the floor in interchange.
Programmatic. Agents already hold USDC — no card-vault step, no PCI scope, no chargebacks.
Verifiable. Every settlement is on-chain at basescan.org/address/0x3b9F…59e.

Compatibility matrix

AP2 requirement	tools402 implementation	Status
Payment-rail neutrality	USDC on Base via EIP-3009 or external facilitator (Coinbase/Cloudflare/PayAI)	✓
Intent Mandate semantics	EIP-712 typed data, max_spend + expires + nonce	✓
Mandate redemption signal	`X-AP2-Mandate-Accepted` header on every paid response	✓
Independent audit	`/v1/_audit/<txHash>` + Basescan	✓
Refundability	On-chain refund possible — wallet-to-wallet, no chargeback window	✓
User consent (KYC, identity)	Out of scope — tools402 never sees a human user; the agent's owner signs the mandate off-platform	—

References

AP2 spec: github.com/google-agentic-commerce/AP2
x402 spec: x402.org
EIP-712: eips.ethereum.org/EIPS/eip-712
EIP-3009: eips.ethereum.org/EIPS/eip-3009
tools402 audit: basescan.org/address/0x3b9F…59e