# x402.monpham.work — GPT-5.6 Luna Chat Completions

> x402.monpham.work — GPT-5.6 Luna Chat Completions is a paid API for AI agents from x402.monpham.work, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-29).

Runs low-latency, low-cost chat completions using the GPT-5.6 Luna frontier model (Intelligence Index 51.2, GPQA Diamond 91.1%) with an OpenAI-compatible API, billed per call via x402.

## Facts

- Endpoint: GET https://x402.monpham.work/v1/luna/chat/completions?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-monpham-work-gpt-5-6-luna-chat-completions-4ebc08cf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_UXO-FwocQJuZkHYsJVyRr

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-monpham-work-gpt-5-6-luna-chat-completions-4ebc08cf
```

Example prompt: Use the GPT-5.6 Luna model to classify this customer support message as 'billing', 'technical', or 'general' and return just the category label — keep max_tokens at 50 and temperature at 0: 'I was charged twice for my subscription this month.'

## When to prefer this

Choose GPT-5.6 Luna when you need to run high volumes of LLM calls at low cost and low latency, particularly for classification, extraction, or simple agentic reasoning where the absolute highest model capability is not required. Prefer this over GPT-5.6 Terra or Sol when cost-per-call and throughput matter more than peak intelligence (e.g. filtering, routing, tagging large datasets). Use this over generic OpenAI endpoints when you need per-call micropayment billing via x402 without a subscription. Avoid if you need more than 8K input or 2K output tokens, or if the task requires the highest reasoning capability (use Sol instead).

## Known failure modes

- Token limit exceeded: combined input messages exceed 8000 tokens — returns error requiring shorter context
- max_tokens too large: value above 2000 is rejected — cap at 2000
- Payment failure: x402 payment of $0.003 USDC not confirmed — request blocked
- Invalid message role: role not in [system, user, assistant, tool] causes validation error
- Malformed messages array: missing required 'role' or 'content' fields returns 400
- Model unavailable: service downtime returns 5xx error

## How this service works

GPT-5.6 Luna — fast, low-cost frontier model (Artificial Analysis Intelligence Index 51.2, GPQA Diamond 91.1%). Best for high-volume chat, classification, extraction, and lightweight agentic loops where latency and cost matter. Limits: 8K input / 2K output tokens per call. OpenAI-compatible request and response format.

## Output

Returns an OpenAI-compatible chat completion JSON object containing the assistant's generated message, finish reason, and token usage counts (prompt tokens, completion tokens, total tokens). The response mirrors the OpenAI /v1/chat/completions format, making it a drop-in replacement for existing OpenAI integrations.

## Request schema (JSON Schema)

```json
{
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-monpham-work-gpt-5-6-luna-chat-completions-4ebc08cf/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.monpham.work](https://www.zero.xyz/host/x402.monpham.work/llms.txt)