# Zero-Hallucination JSON Pack – Battle-Tested LLM System Prompts

> Zero-Hallucination JSON Pack – Battle-Tested LLM System Prompts is a paid API for AI agents from robotshop.up.railway.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Purchases a curated pack of system prompts and few-shot schema directives engineered to force GPT-4o, Claude 3.5, and Gemini to output strict, machine-parsable JSON.

## Facts

- Endpoint: GET https://robotshop.up.railway.app/api/v1/products/prod-zero-hallucination-json-pack/buy?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/zero-hallucination-json-pack-battle-tested-llm-system-prompts-c0e7aaa8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_V05zerUZl5zfVJsa2P9ds

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 zero-hallucination-json-pack-battle-tested-llm-system-prompts-c0e7aaa8
```

Example prompt: Buy me the zero-hallucination JSON prompt pack — I need battle-tested system prompts and few-shot directives that force GPT-4o, Claude 3.5, and Gemini to always return strict machine-parsable JSON.

## When to prefer this

Choose this endpoint when you need ready-made, proven system prompts and few-shot directives specifically designed to enforce strict JSON output across GPT-4o, Claude 3.5, and Gemini — rather than writing and testing your own prompt engineering from scratch. It is best suited for developers and agents who need to quickly integrate reliable structured-output enforcement into multi-model pipelines without the trial-and-error of building custom prompts.

## Known failure modes

- Payment not processed — endpoint returns 402 if x402 payment fails
- Invalid or missing client_id may cause request rejection
- Network timeout on the Railway deployment could result in no response
- Service may return 404 if the product ID has changed or been delisted
- Response may be delayed if the Railway instance is cold-starting

## How this service works

Battle-tested system prompts & few-shot schema directives forcing LLMs (GPT-4o, Claude 3.5, Gemini) to return strict, machine-parsable JSON.

## Output

A downloadable pack of battle-tested system prompts and few-shot schema directives specifically engineered to coerce GPT-4o, Claude 3.5, and Gemini into returning strict, machine-parsable JSON without hallucinated fields, missing keys, or free-form prose contamination.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "client_id": {
   "type": "string",
   "description": "Optional calling agent or client ID"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/zero-hallucination-json-pack-battle-tested-llm-system-prompts-c0e7aaa8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from robotshop.up.railway.app](https://www.zero.xyz/host/robotshop.up.railway.app/llms.txt)