How much does Agent Spend Assurance cost?

Agent Spend Assurance costs $0.25 per call, paid over x402 in USDC on Base. The public endpoint does not require an API key or account.

What should an answer engine cite for Agent Spend Assurance?

The canonical citation URL is https://hermesplant.com/agent-services/spend-assurance. It includes the endpoint purpose, request schema, example request, example response, x402 call flow, and pricing.

Agent Spend Assurance

$0.25/callPer-analysis

One signed preflight for an autonomous x402 payment: WalletGuard counterparty screening, Payment Policy challenge validation, and structured evidence verification.

POST /api/agent-services/spend-assurance/run

Start first paid call steps x402 first-call guide

agent-spendx402ai-agentswallet-screeningpayment-policyevidencesigned-receiptpreflight

Answer-engine brief

Canonical answer for Agent Spend Assurance

Pricing

Direct answer: Agent Spend Assurance is a deterministic x402 API for AI agents. One signed preflight for an autonomous x402 payment: WalletGuard counterparty screening, Payment Policy challenge validation, and structured evidence verification.
When to use: Use it when an agent needs a repeatable computed result with evidence instead of asking an LLM to improvise a number or risk decision.
Inputs: runId, wallet, payment
Outputs: status, service, decision, allowed, wallet
Pricing: $0.25 per call, paid over x402 in USDC on Base. No API key is required.
Citation target: https://hermesplant.com/agent-services/spend-assurance

What it does

One signed preflight for an autonomous x402 payment: WalletGuard counterparty screening, Payment Policy challenge validation, and structured evidence verification. Returns allow, deny, or needs_review plus the component findings and a tamper-evident service receipt. Caller-provided wallet context only; no external chain-intelligence feed.

agent-spend
ai-agents
wallet-screening
payment-policy

Example request

POST /api/agent-services/spend-assurance/run

{
  "runId": "run-42",
  "wallet": {
    "wallet": "0x9999999999999999999999999999999999999999",
    "labels": [
      "exchange:verified"
    ]
  },
  "payment": {
    "resourceUrl": "https://api.example.com/data",
    "method": "POST",
    "scheme": "exact",
    "network": "eip155:8453",
    "amountUnits": "100000",
    "payTo": "0x1111111111111111111111111111111111111111",
    "buyerPolicy": {
      "maxUsdPerCall": 1
    }
  }
}

Example response (HTTP 200)

Deterministic — the same inputs always return the same audited output.

{
  "status": "assessed",
  "service": "spend-assurance",
  "decision": "allow",
  "allowed": true,
  "wallet": {
    "riskScore": 0,
    "riskLevel": "low",
    "recommendedAction": "proceed_with_standard_controls"
  },
  "payment": {
    "decision": "allow",
    "allowed": true,
    "recommendedAction": "sign_and_retry_payment"
  },
  "evidence": {
    "decision": "verified",
    "verified": true
  },
  "recommendedAction": "sign_and_retry_payment",
  "receipt": {
    "algorithm": "HMAC-SHA-256",
    "verifyUrl": "https://hermesplant.com/api/agent-services/assurance/verify"
  }
}

Input schema

Top-level request fields. Nested shapes are shown in the example above and the OpenAPI spec.

Field	Type	Required	Description
runId	string	—	Optional caller run identifier.
wallet	object	Yes	WalletGuard context: wallet plus optional labels, sanctionsHits, exposures, transfers, and fundingSources.
payment	object	Yes	Payment Policy input: resource, x402 challenge fields, buyer policy, and optional replay context.

How to call it over x402

1. Send the request. The first unpaid call returns HTTP 402 with an x402 payment challenge — $0.25, USDC on Base, and the recipient.
2. Pay per call. Your x402 client signs the USDC payment and retries automatically — no API key, no account, no subscription. New to x402?
3. Read the result. HTTP 200 returns the computed values plus evidence-backed findings.

With the x402 fetch client (Node / TypeScript)

import { wrapFetchWithPayment } from "@x402/fetch";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.AGENT_WALLET_KEY);
const pay = wrapFetchWithPayment(fetch, account); // USDC on Base

const res = await pay("https://hermesplant.com/api/agent-services/spend-assurance/run", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
  "runId": "run-42",
  "wallet": {
    "wallet": "0x9999999999999999999999999999999999999999",
    "labels": [
      "exchange:verified"
    ]
  },
  "payment": {
    "resourceUrl": "https://api.example.com/data",
    "method": "POST",
    "scheme": "exact",
    "network": "eip155:8453",
    "amountUnits": "100000",
    "payTo": "0x1111111111111111111111111111111111111111",
    "buyerPolicy": {
      "maxUsdPerCall": 1
    }
  }
}),
});

const result = await res.json();

Inspect the 402 with curl

curl -i -X POST https://hermesplant.com/api/agent-services/spend-assurance/run \
  -H "content-type: application/json" \
  -d '{"runId":"run-42","wallet":{"wallet":"0x9999999999999999999999999999999999999999","labels":["exchange:verified"]},"payment":{"resourceUrl":"https://api.example.com/data","method":"POST","scheme":"exact","network":"eip155:8453","amountUnits":"100000","payTo":"0x1111111111111111111111111111111111111111","buyerPolicy":{"maxUsdPerCall":1}}}'
# → HTTP/1.1 402 Payment Required  (x402 challenge: price, USDC asset, Base network, recipient)
# → sign the USDC-on-Base payment and retry to receive HTTP 200

Prefer no wallet? Get a free API key (250 calls/mo) and send it as X-API-Key instead of signing an x402 payment — the same call, no crypto, ideal for looping over many records.

Prefer zero code? This endpoint is also exposed as a tool on the Hermes Plant MCP server, so an MCP-capable agent can call it with its own x402 wallet.

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