# x402engine GPT-5.6 Luna Pro LLM

> x402engine GPT-5.6 Luna Pro LLM is a paid API for AI agents from x402engine.app, paid per call via x402, $0.00486/call, status unknown (last checked 2026-10-12).

Runs a GPT-5.6-Luna-Pro chat completion request via micropayment-gated API, returning an OpenAI-compatible response for $0.00486 USDC per call.

## Facts

- Endpoint: POST https://x402engine.app/api/llm/gpt-5.6-luna-pro?utm_source=zero.xyz
- Price: $0.00486/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402engine-gpt-5-6-luna-pro-llm-e3267d9e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ra7BJgEIYXEz9HAcB6I4h

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 x402engine-gpt-5-6-luna-pro-llm-e3267d9e -d '<json body>'
```

Example prompt: Send this conversation to GPT-5.6 Luna Pro and get a reply: system says 'you are a helpful assistant', user says 'Summarize the key risks of investing in meme coins in 3 bullet points' — pay per call with USDC.

## When to prefer this

Choose this endpoint when you need access to GPT-5.6 Luna Pro specifically without a monthly OpenAI subscription, want strict per-call cost control using USDC micropayments on Base/Solana/MegaETH, or are building an AI agent that must pay for LLM calls autonomously using the x402 HTTP 402 payment protocol. Prefer this over self-managed OpenAI keys when operating serverless or agent-native architectures where pay-per-use is more economical than flat subscriptions.

## Known failure modes

- Payment not settled — 402 returned if USDC balance is insufficient
- Invalid messages array — 400 if required messages field is missing
- Model unavailable — 503 if GPT-5.6 Luna Pro is temporarily down
- Malformed tool definition — 400 if tool object lacks required function field
- Stream timeout — connection drop if SSE stream is not consumed promptly
- Seed not supported — ignored silently or error if model doesn't support it

## How this service works

125 production APIs behind HTTP 402 micropayments. 87 LLMs, Kling V3 and Hailuo video generation, image generation, code execution, travel search, web scraping, TTS, and transaction simulation. Pay with USDC on Base, USDm on MegaETH, or USDC on Solana.

## Output

Returns an OpenAI-compatible JSON chat completion object with the assistant's message content, finish reason, model name, and optionally tool calls. Streaming mode returns SSE chunks after payment settlement.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "bodyType",
    "body",
    "method"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "messages"
     ],
     "properties": {
      "seed": {
       "type": "integer",
       "description": "Model-supported seed; see /docs/llm-capabilities.md."
      },
      "tools": {
       "type": "array",
       "items": {
        "type": "object",
        "required": [
         "function"
        ],
        "properties": {
         "type": {
          "enum": [
           "function"
          ],
          "type": "string"
         },
         "function": {
          "type": "object",
          "properties": {
           "name": {
            "type": "string"
           },
           "strict": {
            "type": "boolean"
           },
           "parameters": {
            "type": "object"
           },
           "description": {
            "type": "string"
           }
          }
         }
        }
       },
       "description": "Client-executed function definitions; return results using role=tool and tool_call_id."
      },
      "stream": {
       "type": "boolean",
       "description": "Return live OpenAI-compatible SSE after payment settlement."
      },
      "plugins": {
       "type": "array",
       "items": {
        "type": "object",
        "required": [
         "pdf"
        ],
        "properties": {
         "id": {
          "enum": [
           "file-parser"
          ],
          "type": "string"
         },
         "pdf": {
          "type": "object",
          "properties": {
           "engine": {
            "enum": [
             "native"
            ],
            "type": "string"
           }
          }
         }
        }
       },
       "description": "Optional native PDF parser only; automatically enabled for file inputs."
      },
      "messages": {
       "type": "array",
       "items": {
        "type": "object",
        "anyOf": [
         {
          "required": [
           "content"
          ]
         },
         {
          "required": [
           "tool_calls"
          ]
         }
        ],
        "required": [
         "role"
        ],
        "properties": {
         "name": {
          "type": "string"
         },
         "role": {
          "enum": [
           "system",
   
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "model": "openai/gpt-5.6-luna-pro",
  "choices": [
   {
    "index": 0,
    "message": {
     "role": "assistant",
     "content": "Hello!"
    },
    "finish_reason": "stop"
   }
  ],
  "content": "Hello!"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402engine-gpt-5-6-luna-pro-llm-e3267d9e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402engine.app](https://www.zero.xyz/host/x402engine.app/llms.txt)