# Agent Buyer Identity Preflight | x402 Purchase Governance – RPC Capability Probe

> Agent Buyer Identity Preflight | x402 Purchase Governance – RPC Capability Probe is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.005009/call, status unknown (last checked 2026-10-27).

Checks whether a requested set of RPC methods on a given blockchain network are accessible and appropriate before an AI agent purchases an x402-gated RPC endpoint.

## Facts

- Endpoint: GET https://base-agent-preflight.bytoken2023.workers.dev/v1/x402/chain/rpc-capability-probe?utm_source=zero.xyz
- Price: $0.005009/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-27
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-buyer-identity-preflight-x402-purchase-governance-rpc-5b647d9d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_s3dCRQhlQQmYyplOKdAnW

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 agent-buyer-identity-preflight-x402-purchase-governance-rpc-5b647d9d
```

Example prompt: Before spending USDC on this x402 RPC tool, check whether eth_call, eth_getLogs, and eth_getTransactionReceipt are all supported on Base (eip155:8453) and tell me the risk score.

## When to prefer this

Use this endpoint when an AI agent needs to verify RPC method availability and purchase policy fit on a specific blockchain network before committing USDC via x402. Prefer this over generic RPC health checks when you need a structured risk assessment tied to x402 purchase governance, especially when the workflow has specific method, WebSocket, or historical block requirements.

## Known failure modes

- Missing or invalid 'chain' parameter returns a validation error
- Malformed 'methods' string (non-alphanumeric characters) rejected by pattern validation
- Unsupported or unknown chain identifier may return empty or error assessment
- Network timeout from Cloudflare Worker if upstream RPC is unreachable
- requires_trace or requires_websocket set to a non-boolean string returns schema error

## 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

A JSON object containing the network identifier, product name, an assessment object with a risk score (0–1 numeric), risk level string (e.g. 'low'), and any raised flags, plus optional activity, identity, and provenance sub-objects that describe the capability probe outcome.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "chain",
      "methods"
     ],
     "properties": {
      "chain": {
       "type": "string",
       "pattern": "^[A-Za-z0-9:_ -]{2,80}$",
       "description": "Requested chain or CAIP-2 network label."
      },
      "methods": {
       "type": "string",
       "pattern": "^[A-Za-z0-9_.,:-]{2,400}$",
       "description": "Comma-separated RPC methods the workflow needs."
      },
      "requires_trace": {
       "type": "string",
       "pattern": "^(?:true|false)$",
       "description": "Whether debug/trace methods are required."
      },
      "historical_block": {
       "type": "string",
       "pattern": "^[0-9]{1,12}$",
       "description": "Optional historical block number needed by the workflow."
      },
      "requires_websocket": {
       "type": "string",
       "pattern": "^(?:true|false)$",
       "description": "Whether subscription/WebSocket support is required."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "network": {
       "type": "string"
      },
      "product": {
       "type": "string"
      },
      "activity": {
       "type": "object"
      },
      "identity": {
       "type": "object"
      },
      "assessment": {
       "type": "object"
      },
      "provenance": {
       "type": "object"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "network": "eip155:8453",
  "product": "rpc-capability-probe",
  "assessment": {
   "flags": [],
   "risk_level": "low",
   "risk_score": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-buyer-identity-preflight-x402-purchase-governance-rpc-5b647d9d/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)