# X402 Price Drift Check

> X402 Price Drift Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-21).

Compares an advertised x402 price against a challenged price and accepts or rejects the result if the drift exceeds a caller-supplied tolerance, returning a deterministic verdict with mismatch reasons.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/x402-price-drift-check?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-price-drift-check-3edeb8aa
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Nfl3DEWFzsa5GGQZuOPjc

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 x402-price-drift-check-3edeb8aa -d '<json body>'
```

Example prompt: Before we pay this x402 invoice, check the price drift: the advertised price is '1000000' raw units, the challenged price is '1050000' raw units, and our maximum allowed drift is '20000' raw units — tell me if this is safe to accept.

## When to prefer this

Use this endpoint when operating in an x402 or agentic payment flow and you need a fast, deterministic, serverless drift check between an advertised price and a challenged price before committing to a payment or accepting a delivery. It is preferable over manual comparison logic when you need a versioned, auditable verdict with mismatch reasons and normalized evidence, and when no external oracle or live price feed is involved.

## Known failure modes

- Malformed or non-numeric raw price strings cause a validation error
- Missing required fields (advertised_raw, challenged_raw, maximum_drift_raw) return an error
- Values exceeding the 8192-character maxLength are rejected
- Ambiguous or non-comparable raw formats may produce inconclusive results

## How this service works

X402 Price Drift Check: X402 Price Drift Check compares advertised and challenged raw prices against a tolerance from bounded caller-supplied values without an external provider. Call X402 Price Drift Check before paying for or accepting an x402 or agent delivery assembled from caller-supplied challenge and result metadata. Returns contract-specific checks, normalized evidence, mismatch reasons, and an explicit acceptance or rejection status for X402 Price Drift Check as versioned deterministic…

## Output

Returns a structured response with an explicit acceptance or rejection status, contract-specific validation checks, normalized price evidence, and a list of mismatch reasons if the drift between the advertised and challenged raw prices exceeds the supplied maximum drift tolerance. All processing is in-memory with no data retention.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "advertised_raw": {
   "type": "string",
   "maxLength": 8192,
   "description": "Advertised Raw supplied to X402 Price Drift Check; used only for this bounded calculation and processed in memory without retention."
  },
  "challenged_raw": {
   "type": "string",
   "maxLength": 8192,
   "description": "Challenged Raw supplied to X402 Price Drift Check; used only for this bounded calculation and processed in memory without retention."
  },
  "maximum_drift_raw": {
   "type": "string",
   "maxLength": 8192,
   "description": "Maximum Drift Raw supplied to X402 Price Drift Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "drift_raw": "0",
   "actual_raw": "1000",
   "expected_raw": "1000",
   "within_tolerance": true
  },
  "schema": "delx/util-x402-price-drift-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "5f37133d31b2d093bb549e808c67f9a515cc5ce68e1a0cd15a614b31b5894fdf",
   "external_calls": 0
  },
  "operation": "delivery_contract:x402_price_drift_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-price-drift-check-3edeb8aa/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)