# x402 Endpoint Preflight Inspector

> x402 Endpoint Preflight Inspector is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.015002/call, status unknown (last checked 2026-10-10).

Inspects a public HTTP/HTTPS x402-payment-gated URL and returns risk assessment, network metadata, and safety flags without actually paying the endpoint's fee.

## Facts

- Endpoint: GET https://base-agent-preflight.bytoken2023.workers.dev/v1/x402/web/endpoint-preflight?utm_source=zero.xyz
- Price: $0.015002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-endpoint-preflight-inspector-0720e55a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_PMNsNHDEh14omLZ_K8QOY

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 x402-endpoint-preflight-inspector-0720e55a
```

Example prompt: Before we pay for it, can you do a preflight safety check on this x402 endpoint — https://api.example.com/v1/some-paid-resource — and tell me the risk score and any flags it raises?

## When to prefer this

Use this endpoint when an autonomous agent needs to evaluate an x402-gated URL before committing payment, specifically to get a machine-readable risk score and safety flags. Prefer this over generic URL checkers when working within the x402 payment protocol ecosystem on Base network, as it understands x402-specific metadata, identity, and provenance signals.

## Known failure modes

- URL is not a valid HTTP/HTTPS address — returns validation error
- Target URL is unreachable or returns non-x402 response — may return empty or error assessment
- URL exceeds 2048 character limit — schema validation failure
- Non-GET method specified — rejected by schema constraint
- Target endpoint is private or firewalled — inspection returns incomplete data

## 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 Base network identifier (e.g. eip155:8453), product name, and an assessment object with a risk_score (numeric), risk_level (e.g. 'low'), and an array of flags describing any detected issues. May also include activity, identity, and provenance sub-objects with additional metadata about the endpoint.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "network": "eip155:8453",
  "product": "x402-endpoint-preflight",
  "assessment": {
   "flags": [],
   "risk_level": "low",
   "risk_score": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-endpoint-preflight-inspector-0720e55a/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)