# CURB Discovery Probe (x402 USDC on Base)

> CURB Discovery Probe (x402 USDC on Base) is a paid API for AI agents from api.curb.numetal.xyz, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).

A paid discovery probe endpoint that accepts a small USDC payment via x402 protocol on Base and returns a sample response, used to verify the service is live and payment-gated correctly.

## Facts

- Endpoint: POST https://api.curb.numetal.xyz/v1/matches/match_mrds8oip_123bf3b7/pay
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/curb-discovery-probe-x402-usdc-on-base-715a8d05
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qxkEBRkUJ40ja1N8_f-gA

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 curb-discovery-probe-x402-usdc-on-base-715a8d05 -d '<json body>'
```

Example prompt: Run a discovery probe on the CURB match endpoint — send the $0.10 USDC x402 payment on Base and include the note 'test probe' to confirm the payment-gated API is live and responding correctly.

## When to prefer this

Use this endpoint when you need to verify that an x402 USDC-gated API on Base is operational, or when testing the end-to-end micropayment flow for a CURB discovery probe. It is ideal for confirming API availability before integrating further, or for developers validating their x402 payment infrastructure against a live endpoint.

## Known failure modes

- Insufficient USDC balance — payment rejected, 402 Payment Required returned
- Invalid x402 payment header — authentication or payment verification fails
- Network issues with Base blockchain — transaction cannot be confirmed
- Endpoint unavailable — 503 or timeout if service is down
- Malformed request body — 400 Bad Request if JSON is invalid

## How this service works

CURB discovery probe — USDC x402 on Base (sample price)

## Output

The agent receives a probe response confirming the endpoint is reachable and that the x402 USDC payment on Base was processed successfully; may include match metadata or a sample payload demonstrating the endpoint is operational.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "note": {
   "type": "string",
   "description": "Optional; ignored on unpaid probe."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/curb-discovery-probe-x402-usdc-on-base-715a8d05/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.curb.numetal.xyz](https://www.zero.xyz/host/api.curb.numetal.xyz/llms.txt)