# x402-gateway GPT-5.2 Pro (Premium Reasoning LLM)

> x402-gateway GPT-5.2 Pro (Premium Reasoning LLM) is a paid API for AI agents from x402-gateway-production.up.railway.app, paid per call via x402, $0.25/call, status unknown (last checked 2026-09-15).

Calls OpenAI's GPT-5.2 Pro premium reasoning model for extended thinking on complex math, science, and coding problems via the x402 pay-per-call gateway

## Facts

- Endpoint: POST https://x402-gateway-production.up.railway.app/api/llm/gpt-5.2-pro
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-gateway-production-up-railway-app-30470af4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_CuUz7lSdTS-hxcR9zp6O4

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-gateway-production-up-railway-app-30470af4 -d '<json body>'
```

Example prompt: Use GPT-5.2 Pro's extended reasoning to solve this: prove that there are infinitely many prime numbers using at least two distinct proof methods, and then write an optimized Python sieve of Eratosthenes with time complexity analysis.

## When to prefer this

Choose this endpoint when the task requires deep, multi-step reasoning — such as advanced mathematics, rigorous scientific analysis, complex algorithm design, or hard debugging — where a standard LLM would fall short. Prefer this over cheaper or faster models when answer quality and extended thinking capability matter more than cost or latency.

## Known failure modes

- Payment not processed — x402 payment header missing or USDC balance insufficient
- Model unavailable or overloaded — 503 or timeout from upstream OpenAI API
- Malformed request body — missing required prompt or message field
- Rate limit exceeded on the gateway
- Invalid or expired API credentials on the gateway side

## How this service works

OpenAI's premium reasoning model — extended thinking for complex math, science, and coding problems

## Output

A richly detailed text response generated by GPT-5.2 Pro, leveraging extended chain-of-thought reasoning to address complex mathematical, scientific, or coding questions with depth and rigor.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-gateway-production-up-railway-app-30470af4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-gateway-production.up.railway.app](https://www.zero.xyz/host/x402-gateway-production.up.railway.app/llms.txt)