# CounterpartyCheck > CounterpartyCheck is a paid API for AI agents from counterparty.agentgate.workers.dev, paid per call via x402, $0.05/call, status unknown (last checked 2026-10-30). Pre-payment due diligence on a blockchain address: returns a single ok/caution/block verdict with OFAC, scam, contract-type, and activity signals before you pay, approve, or interact. ## Facts - Endpoint: GET https://counterparty.agentgate.workers.dev/v1/full?utm_source=zero.xyz - Price: $0.05/call - Payment: x402 - Status: unknown - Last checked: 2026-10-30 - Activations on Zero: 0 - Tags: x402 - Canonical page: https://www.zero.xyz/c/counterpartycheck-8fb865f0 - Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XuNChps9brePB_yLeJa1- 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 counterpartycheck-8fb865f0 ``` Example prompt: Before I send the payment, can you run a safety check on 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913 on Base and tell me if it's safe to pay — like whether it's a real wallet, if it's flagged by OFAC or ScamSniffer, and what the overall verdict is? ## When to prefer this Use this endpoint when an AI agent is about to execute or authorize any on-chain action — payment, token approval, or contract interaction — and needs a fast, single-call safety verdict before proceeding. It uniquely composes OFAC SDN, ScamSniffer, x402 Bazaar directory, contract-type classification, ENS/Basename resolution, and TokenVerdict into one response, saving agents from building multi-source pipelines. Prefer it over raw blockchain RPC calls when you need a human-readable risk decision rather than raw on-chain data. ## Known failure modes - Invalid or malformed address format returns an error - Unsupported chain returns a validation error - Unknown or brand-new address may return low confidence with missing_data populated - Rate limiting or upstream data source outages may degrade signal quality - Solana address on an EVM chain (or vice versa) may fail or return misleading results - No guarantee of completeness — free public data only, informational only ## How this service works Pre-payment due diligence for AI agents: before paying, approving or interacting with an address on Base, Ethereum, Polygon, Arbitrum One or Solana, get one decision (ok / caution / block) with reasons, a confidence and missing_data. Composes OFAC SDN and ScamSniffer screening, the x402 Bazaar payee directory, wallet vs contract vs token vs Safe vs EIP-7702, verification and deployer, ENS / Basename, cross-chain presence, age, recent activity and exposure, approvals and TokenVerdict. Free public data only; informational safety check, no guarantees. ## Output A JSON object with: a top-level verdict (ok/caution/block), a confidence level (high/medium/low), a human-readable summary, an array of reasons each with a code, text, and severity, plus facts about the address (kind, token info, ENS/Basename, deployer, age, cross-chain presence, recent activity, approvals) and a missing_data field indicating gaps in available data. ## 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": [ "address" ], "properties": { "chain": { "enum": [ "base", "ethereum", "polygon", "arbitrum", "solana" ], "type": "string", "description": "Chain of the payment (default base; a base58 address implies solana)" }, "intent": { "enum": [ "pay", "approve", "interact" ], "type": "string", "description": "What you are about to do (default pay): changes which signals matter, e.g. paying a token contract or approving an EOA" }, "address": { "type": "string", "description": "Counterparty address: EVM 0x + 40 hex, or a Solana base58 address" } }, "description": "Search intents: full wallet due diligence, address exposure check, drainer approvals check, wallet age, crypto risk report, counterparty aml" } }, "additionalProperties": false }, "output": { "type": "object", "required": [ "type" ], "properties": { "type": { "type": "string" }, "example": { "type": "object", "properties": { "tier": { "type": "string" }, "chain": { "type": "string" }, "facts": { "type": "object" }, "checks": { "type": "object" }, "intent": { "type": "string" }, "address": { "type": "string" }, "reasons": { "type": "array" }, "summary": { "type": "string" }, "verdict": { "type": "string" }, "confidence": { "type": "string" } } } } } } } ``` ## Response schema (JSON Schema) ```json { "type": "json", "example": { "tier": "full", "chain": "base", "facts": { "kind": "contract", "token": { "symbol": "USDC", "decimals": 6 } }, "checks": { "age": { "at": "2023-08-18T18:36:29.000Z", "days": 1160, "basis": "contract creation block", "block": 2797221, "known": true } }, "intent": "pay", "address": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913", "reasons": [ { "code": "token_contract", "text": "This is the USDC token contract itself, not a wallet: tokens sent to a token contract are usually lost.", "severity": "danger" }, { "code": "known_label", "text": "Known address: USDC (Circle, Base).", "severity": "good" }, { "code": "verified", "text": "Contract source verified on Sourcify (FiatTokenProxy).", "severity": "good" }, { "code": "established", "text": "Established: contract creation block 1160 days ago (2023-08-18).", "severity": "good" } ], "summary": "BLOCK: This is the USDC token contract itself, not a wallet: tokens sent to a token contract are usually lost.", "verdict": "block", "confidence": "high" } } ``` ## More - Live health (JSON, refreshed every minute): https://www.zero.xyz/c/counterpartycheck-8fb865f0/health.json - [Zero catalog index](https://www.zero.xyz/llms.txt) - [Other services from counterparty.agentgate.workers.dev](https://www.zero.xyz/host/counterparty.agentgate.workers.dev/llms.txt)