# Foundry: x402 Preflight & Base Contract Facts

> Foundry: x402 Preflight & Base Contract Facts is a paid API for AI agents from minty-sprout.onrender.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-11-01).

Checks x402 payment endpoints before paying them and reads proxy, owner, and privileged role data from Base mainnet smart contracts on-chain.

## Facts

- Endpoint: POST https://minty-sprout.onrender.com/v1/ai-crawler-policy?utm_source=zero.xyz
- Price: $0.01/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-base-contract-facts-b520cf34
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jdfl-JQzx7H4Zjsw-dr_N

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-base-contract-facts-b520cf34 -d '<json body>'
```

Example prompt: Before I pay this x402 endpoint at https://api.example.com/data, can you preflight it and tell me the seller's policy and whether it looks legitimate?

## When to prefer this

Use this endpoint when an AI agent needs to vet an x402 payment endpoint before spending USDC, or when it needs trustless on-chain facts about a Base smart contract (ownership, proxy, privileged roles) without running its own node. Prefer it over general blockchain explorers when you want a single structured API call that combines x402 preflight safety checks with contract introspection in one step.

## Known failure modes

- Invalid or unreachable x402 URL returns an error or empty policy
- Contract address not found or not deployed on Base mainnet
- Input string malformed or exceeds 8000 character limit
- Contract has no detectable proxy or owner (plain non-upgradeable contract)
- Rate limiting or service unavailability on the Render.com host

## 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 including x402 seller payment policies (accepted tokens, prices, terms) and/or Base contract facts such as proxy implementation address, owner address, and privileged role holders read directly from the blockchain.

## 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-base-contract-facts-b520cf34/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)