# ONE Engine JSON Array Head Utility (Tier 3)

> ONE Engine JSON Array Head Utility (Tier 3) is a paid API for AI agents from one-search.one-engine.workers.dev, paid per call via x402, $0.0008/call, status unknown (last checked 2026-10-12).

Returns the first N items from a JSON array with Tier 3 progressive diagnostics, deterministically processing the input array and returning its head elements.

## Facts

- Endpoint: POST https://one-search.one-engine.workers.dev/v8/array-process/head/p1/t3?utm_source=zero.xyz
- Price: $0.0008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/one-engine-json-array-head-utility-tier-3-c1a3dd39
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Yyc9vFwptaW3zjifgeZTX

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 one-engine-json-array-head-utility-tier-3-c1a3dd39 -d '<json body>'
```

Example prompt: Take this JSON array and give me just the first item from it, using the ONE Engine head utility with Tier 3 diagnostics: [42, 'hello', true, 99].

## When to prefer this

Choose this endpoint when you need a cheap, deterministic, pay-per-call way to extract the first element(s) from a JSON array within an agent workflow, especially when you want Tier 3 diagnostic output for debugging or auditing. Prefer it over custom code when operating in an x402-compatible agent pipeline on Base that needs verifiable, consistent array head operations without managing infrastructure.

## Known failure modes

- Empty array input returns no items or an error
- Non-array JSON body causes a parse or type error
- Malformed JSON payload results in a 400 bad request
- Payment not attached or insufficient USDC causes a 402 response
- Network timeout on the Workers.dev edge

## How this service works

Deterministic JSON array processing utility: Return first array items; parameter=1. Tier 3/10 provides progressively richer diagnostics.

## Output

Returns a JSON object containing the first item (or first N items, where N=1 by default) extracted from the submitted array, along with Tier 3 progressive diagnostics such as processing metadata, input array length, and result confirmation details.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/one-engine-json-array-head-utility-tier-3-c1a3dd39/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from one-search.one-engine.workers.dev](https://www.zero.xyz/host/one-search.one-engine.workers.dev/llms.txt)