# x402check

> Trust-check a tool before your agent pays it. $0.002 USDC Exact per tool. No free tier.

Every check is paid. You get that tool's **verdict** (ok|caution|avoid) plus its **history** (uptime, payTo changes, price changes) — nothing else. Use before PAYMENT-SIGNATURE, to verify payTo, detect drift, compare sellers, or as a budget guard. Cache-fresh responses target <300ms.

## Quick start

```
GET https://x402check.dev/preflight?url=https://seller.example/x402
```

Pay $0.002 via x402 Exact on Base, then retry with PAYMENT-SIGNATURE.

## Machine-readable

- [OpenAPI](https://x402check.dev/openapi.json)
- [llms.txt](https://x402check.dev/llms.txt)
- [MCP Server Card](https://x402check.dev/mcp/server-card)
- [A2A Agent Card](https://x402check.dev/.well-known/agent-card.json)
- [AI Catalog](https://x402check.dev/.well-known/ai-catalog.json)

## Docs

See [docs.md](https://x402check.dev/docs.md) or [docs](https://x402check.dev/docs).