# SignGate Agent Payment Execution Readiness Check > SignGate Agent Payment Execution Readiness Check is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14). Verifies whether an AI agent's payment intent for an x402 API or dataset meets buyer identity, policy, and risk governance rules before the transaction executes. ## Facts - Endpoint: GET https://base-agent-preflight.bytoken2023.workers.dev/v1/x402/agent/payment-execution-readiness - Price: $0.05/call - Payment: x402 - Status: unknown - Last checked: 2026-09-14 - Activations on Zero: 0 - Tags: x402 - Canonical page: https://www.zero.xyz/c/signgate-agent-payment-execution-readiness-check-1fec6477 - Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EN6FEmzT8Y9Mh0Npb2so8 Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently. ## How to call it through Zero Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`): ```sh zero fetch --capability signgate-agent-payment-execution-readiness-check-1fec6477 ``` Example prompt: Before my agent pays 12.50 USDC to merchant address 0xAbC...123 for request ID 'req-20240601-analytics-007', run a payment readiness preflight to check whether the buyer wallet 0xDef...456 is authorized, the amount is within policy (daily budget 50 USDC, max single 20 USDC, human review above 15 USDC), and what the risk score looks like. ## When to prefer this Use this endpoint when an AI agent operates autonomously with x402 payment capabilities and you need a lightweight, fast governance check before any USDC transaction executes on the Base network. Prefer it over post-hoc audit when you need to enforce spending caps, flag high-risk purchases for human review, or validate buyer identity and role before committing funds. It is especially valuable in multi-agent fleet deployments where individual agents have session or daily budget constraints. ## Known failure modes - Missing required query parameters (request_id, pay_to, amount_usdc, owner) returns a 400 error - Invalid Ethereum address format for owner, pay_to, spender, or token fields - amount_usdc not matching numeric pattern causes schema rejection - request_id exceeding 128 characters or containing invalid characters is rejected - Service unavailable or Cloudflare Worker timeout returns 5xx - Policy configuration fields (daily_budget_usdc, max_single_usdc) not provided may result in incomplete risk assessment - Unknown agent_id may result in elevated risk score or flags ## How this service works Machine-payable service intelligence for discovering, verifying, and monitoring identity, risk, authorization, execution-preflight, and evidence APIs before autonomous agents spend. ## Output Returns a JSON object containing the network identifier (e.g. eip155:8453 for Base), the product name, and an assessment object with risk_level (e.g. 'low', 'medium', 'high'), a numeric risk_score, and an array of flags identifying any policy violations or concerns — such as budget overages, missing approvals, or identity mismatches. ## Request schema (JSON Schema) ```json { "type": "object", "$schema": "https://json-schema.org/draft/2020-12/schema", "required": [ "input" ], "properties": { "input": { "type": "object", "required": [ "type", "method" ], "properties": { "type": { "type": "string", "const": "http" }, "method": { "enum": [ "GET" ], "type": "string" }, "queryParams": { "type": "object", "required": [ "request_id", "pay_to", "amount_usdc", "owner" ], "properties": { "tx": { "type": "string", "pattern": "^0x[a-fA-F0-9]{64}$", "description": "Optional prior transaction hash for receipt evidence." }, "owner": { "type": "string", "pattern": "^0x[a-fA-F0-9]{40}$", "description": "Wallet or token owner expected to execute payment." }, "token": { "type": "string", "pattern": "^0x[a-fA-F0-9]{40}$", "description": "ERC-20 token used for the payment or approval check." }, "pay_to": { "type": "string", "pattern": "^0x[a-fA-F0-9]{40}$", "description": "Recipient or API merchant payment address." }, "purpose": { "type": "string", "maxLength": 160, "description": "Business purpose for the payment." }, "spender": { "type": "string", "pattern": "^0x[a-fA-F0-9]{40}$", "description": "Address approved or expected to spend the owner's token." }, "agent_id": { "type": "string", "maxLength": 120, "description": "Agent identity or internal principal." }, "gas_limit": { "type": "string", "pattern": "^[0-9]+$", "description": "Expected transaction gas limit." }, "request_id": { "type": "string", "pattern": "^[A-Za-z0-9._:-]{1,128}$", "description": "Idempotent payment intent or policy request id." }, "amount_usdc": { "type": "string", "pattern": "^[0-9]+(?:\\.[0-9]{1,6})?$", "description": "Requested payment amount in USDC." }, "max_single_usdc": { "type": "string", "pattern": "^[0-9]+(?:\\.[0-9]{1,6})?$", "description": "Policy max single payment." }, "daily_budget_usdc": { "type": "string", "pattern": "^[0-9]+(?:\\.[0-9]{1,6})?$", "description": "Policy daily budget." }, "session_budget_usdc": { "type": "string", … (truncated) ``` ## Response schema (JSON Schema) ```json { "type": "json", "example": { "network": "eip155:8453", "product": "agent-payment-execution-readiness", "assessment": { "flags": [], "risk_level": "low", "risk_score": 0 } } } ``` ## More - Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signgate-agent-payment-execution-readiness-check-1fec6477/health.json - [Zero catalog index](https://www.zero.xyz/llms.txt) - [Other services from base-agent-preflight.bytoken2023.workers.dev](https://www.zero.xyz/host/base-agent-preflight.bytoken2023.workers.dev/llms.txt)