# Foundry: x402 Preflight and Base Contract Facts

> Foundry: x402 Preflight and Base Contract Facts is a paid API for AI agents from minty-sprout.onrender.com, paid per call via x402, $0.03/call, status unknown (last checked 2026-11-01).

Checks x402 payment endpoints before paying them and reads Base blockchain contracts for proxy, owner, and privileged role information directly from the chain.

## Facts

- Endpoint: POST https://minty-sprout.onrender.com/v1/schema-extract-guarded?utm_source=zero.xyz
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/foundry-x402-preflight-and-base-contract-facts-b5695599
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fGLCYvsF8ldc3BpCWSros

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 foundry-x402-preflight-and-base-contract-facts-b5695599 -d '<json body>'
```

Example prompt: Before I pay this x402 endpoint at https://api.example.com/data, run a preflight check on it and also tell me who owns the Base contract at 0xABC123... and whether it uses a proxy.

## When to prefer this

Use this endpoint when an AI agent needs to vet an x402 payment endpoint before committing USDC, or when it needs to read ownership and proxy structure of a Base network smart contract without setting up a direct RPC connection. Prefer this over generic blockchain explorers when you need structured, agent-ready output for x402 ecosystem due diligence specifically.

## Known failure modes

- Invalid or unreachable x402 URL returns an error or empty seller info
- Contract address not found on Base returns null or not-deployed error
- Malformed input string causes a 400-level validation error
- Non-Base contract address (wrong chain) may return no results
- Rate limiting or upstream RPC failures may cause timeouts

## How this service works

Pay-per-call data for agents: check x402 sellers before paying them, and read Base contracts' proxy, owner and privileged powers straight from the chain.

## Output

Returns structured data about an x402 seller (metadata, legitimacy signals) and/or a Base contract's proxy configuration, owner address, and privileged role assignments read directly from on-chain state.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "input": {
   "type": "string",
   "maxLength": 8000
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/foundry-x402-preflight-and-base-contract-facts-b5695599/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from minty-sprout.onrender.com](https://www.zero.xyz/host/minty-sprout.onrender.com/llms.txt)