# 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 2026-09-14).

A paid discovery probe endpoint that validates x402 micropayment flows on Base using USDC, returning a match result for a specific CURB match ID.

## Facts

- Endpoint: POST https://api.curb.numetal.xyz/v1/matches/match_mrdr29vy_bb1e15ed/pay
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/curb-discovery-probe-x402-usdc-on-base-f83cfec1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_V7qtQONB1eSt89wGImP67

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-f83cfec1 -d '<json body>'
```

Example prompt: Run a CURB discovery probe on match ID match_mrdr29vy_bb1e15ed using a 0.1 USDC x402 payment on Base, and include the note 'testing probe flow'.

## When to prefer this

Use this endpoint when you need to test or validate an x402 micropayment discovery flow on Base using USDC, specifically against a known CURB match probe. Prefer this over generic API test endpoints when the goal is to confirm x402 protocol compliance and USDC payment acceptance in the CURB ecosystem.

## Known failure modes

- Payment not included or malformed x402 header returns 402 Payment Required
- Insufficient USDC balance causes payment failure
- Invalid or expired match ID returns 404 Not Found
- Network congestion on Base delays payment confirmation
- Malformed request body returns 400 Bad Request

## How this service works

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

## Output

A probe response confirming whether the x402 USDC payment on Base was accepted and returning match metadata for the given CURB match ID, validating the discovery flow end-to-end.

## 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-f83cfec1/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)