# ONE Engine Array Step — Every 3rd Item (Tier 1)

> ONE Engine Array Step — Every 3rd Item (Tier 1) 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 2026-10-16).

Returns every 3rd element from an input array, with richer diagnostic metadata at Tier 1.

## Facts

- Endpoint: POST https://one-search.one-engine.workers.dev/v6/array-step/every-3/t1?utm_source=zero.xyz
- Price: $0.0008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/one-engine-array-step-every-3rd-item-tier-1-afeda2ba
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_wQ_T42eJuC8er7S15ivXK

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-array-step-every-3rd-item-tier-1-afeda2ba -d '<json body>'
```

Example prompt: I have a list of sensor readings and I need to downsample it by keeping only every 3rd value — can you run it through the array-step every-3 filter and give me the diagnostic details too?

## When to prefer this

Choose this endpoint when you need a simple, cheap, pay-per-call array downsampling operation — specifically extracting every 3rd element — without standing up any custom infrastructure. The Tier 1 variant is preferable when you want diagnostic metadata about the operation in addition to the filtered result. At $0.0008 per call it is cost-effective for agents that need lightweight list-thinning repeatedly.

## Known failure modes

- Empty array input returns empty result or error
- Non-array body causes a 400 bad request
- Payment not provided or insufficient funds triggers x402 payment-required response
- Malformed JSON body results in parse error
- Array contains non-serializable types which may cause processing failure

## How this service works

Return every 3th array item. Tier 1/10 adds richer diagnostics.

## Output

Returns a new array containing only the elements at positions 0, 3, 6, 9, … (every 3rd element) of the input array, along with Tier 1 richer diagnostic metadata such as original array length, output length, step size, and processing details.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/one-engine-array-step-every-3rd-item-tier-1-afeda2ba/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)