{"uid":"cap_HYUKAoRA6PjJJ-t23ZDuk","slug":"gpt-5-6-luna-chat-completions-x402-openai-compatible-c2b40b33","name":"GPT-5.6 Luna Chat Completions (x402, OpenAI-Compatible)","description":"GPT-5.6 Luna API Base USDC and OpenAI-compatible x402 chat: one request for $0.00293, paid by browser wallet or a quote-first agent fallback.","url":"https://gpt55.558686.xyz/v1/chat/completions/gpt-5.6-luna?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"pathParams":{"type":"object","additionalProperties":true},"queryParams":{"type":"object","properties":{"q":{"type":"string"},"input":{"type":"string"},"model":{"enum":["gpt-5.6-sol","gpt-5.6","gpt-5.6-luna","gpt-5.6-terra","gpt-5.5","gpt-5.3-codex","gpt-5.4"],"type":"string"},"prompt":{"type":"string"},"system":{"type":"string"},"message":{"type":"string"},"max_tokens":{"type":"integer","maximum":128000,"minimum":1},"system_prompt":{"type":"string"},"max_output_tokens":{"type":"integer","maximum":128000,"minimum":1}},"additionalProperties":true}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","required":["id","object","model","choices"],"properties":{"id":{"type":"string"},"model":{"type":"string"},"usage":{"type":"object"},"object":{"type":"string"},"choices":{"type":"array"}},"additionalProperties":true}}}}},"responseSchema":{"type":"json","example":{"id":"chatcmpl_example","model":"gpt-5.6-luna","usage":{"total_tokens":44,"prompt_tokens":32,"completion_tokens":12},"object":"chat.completion","choices":[{"index":0,"message":{"role":"assistant","content":"A concise answer from GPT-5.5."},"finish_reason":"stop"}]}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.019999","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.019999/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.019999","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.019999","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_W-M3n4CSpUqRSs0-X9Doj","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.019999","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Returns an OpenAI-compatible chat completion from the GPT-5.6 Luna model via a pay-per-call GET request priced in USDC over x402.","exampleAgentPrompt":"Using the GPT-5.6 Luna model, answer this question with up to 200 tokens: 'What are three concise tips for reducing cloud infrastructure costs?' — use the system prompt 'You are a helpful cloud cost advisor.'","exampleUseCases":[{"title":"Agent routing decision helper","prompt":"Ask GPT-5.6 Luna to classify this user message into one of three intents — 'purchase', 'support', or 'information' — and return only the label: 'I can't find my order from last week.'"},{"title":"Lightweight buyer triage answer","prompt":"Use the gpt-5.6-luna model to give a one-sentence answer to a potential customer asking 'Is this product compatible with macOS 14?' — keep it under 50 tokens."},{"title":"Context-grounded QA for a knowledge base","prompt":"Send this context snippet and question to GPT-5.6 Luna and get a concise answer: context is 'Our return policy allows returns within 30 days with receipt,' and the question is 'Can I return something I bought 3 weeks ago?'"}],"resultDescription":"A JSON object in OpenAI chat.completion format containing: a unique completion ID, the model name ('gpt-5.6-luna'), an array of choices each with an assistant message and finish_reason, and a usage object with prompt_tokens, completion_tokens, and total_tokens.","failureModes":["Payment not included or insufficient USDC causes 402 Payment Required with a payment challenge","Invalid or missing 'model' query parameter returns an error or falls back to default model","Prompt or message too long exceeds max_tokens limit of 128000","GET method limitations mean very long prompts may be truncated by URL length restrictions","Unknown or unsupported model enum value causes rejection","Rate limiting or quota exceeded on the upstream provider returns 429","Domain or infrastructure outage on 558686.xyz returns 5xx"],"whenToPreferThis":"Choose this endpoint when you need a pay-per-call, no-subscription LLM inference endpoint that accepts USDC micropayments via x402 and is OpenAI API-compatible, especially if your agent wallet supports x402 payment flows. It is well-suited for lightweight routing, extraction, short QA, and buyer triage tasks where per-request billing is preferred over a monthly API key subscription. Prefer alternatives (e.g. direct OpenAI API) when you need guaranteed model provenance, SLA, or longer context reliability.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-11T00:45:01.704Z","isFirstParty":false,"canonicalSlug":"gpt-5-6-luna-chat-completions-x402-openai-compatible-c2b40b33"}