{"uid":"cap_MnErCtUL6tFP4LnVvdGuP","slug":"model-access-gateway-gpt-6-luna-chat-completions-x402-usdc-cfa9e717","name":"Model Access Gateway – GPT-6 Luna Chat Completions (x402, USDC)","description":"LLM inference API: OpenAI-compatible chat completions for 136 AI models (Claude, GPT, Gemini, Grok, DeepSeek, Qwen, Kimi, GLM), paid per call in USDC on Base with x402. No account, no API key, automatic refund if the model fails.","url":"https://modelaccessgateway.com/llm/gpt-6-luna?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"model":{"type":"string","description":"Optional: fixed by the route (openai/gpt-6-luna)"},"tools":{"type":"array"},"stream":{"type":"boolean","description":"true: server-sent events after payment"},"messages":{"type":"array","items":{"type":"object","required":["role"],"properties":{"role":{"enum":["system","user","assistant","tool","developer"],"type":"string"},"content":{"type":["string","array","null"]}}},"minItems":1},"max_tokens":{"type":"integer","maximum":16384,"minimum":1,"description":"Optional, default 4096"},"temperature":{"type":"number","maximum":2,"minimum":0},"response_format":{"type":"object"}}},"responseSchema":{"type":"json","example":{"id":"chatcmpl-7f3c2a91","model":"openai/gpt-6-luna","usage":{"total_tokens":10,"prompt_tokens":9,"completion_tokens":1},"object":"chat.completion","choices":[{"index":0,"message":{"role":"assistant","content":"OK"},"finish_reason":"stop"}],"created":1791979200}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.0014","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":"$0.0014/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.0014","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.0014","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_IJ5TnTIBoPTQ5Rplc93sH","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.0014","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Runs OpenAI-compatible chat completions against the gpt-6-luna model, paid per call in USDC via x402 with no account or API key required.","exampleAgentPrompt":"Using the pay-per-call LLM gateway (no API key needed, billed in USDC), send this conversation to GPT-6 Luna: system prompt 'You are a helpful assistant', user message 'Explain quantum entanglement in two sentences', max 300 tokens, temperature 0.7.","exampleUseCases":[{"title":"Autonomous agent reasoning step","prompt":"I need my agent to call GPT-6 Luna through the pay-per-call gateway to reason through this decision: system prompt is 'You are a logical reasoning engine', user message is 'Given these three options, pick the most cost-efficient: A) cloud VM, B) serverless, C) bare metal — with a 5-request-per-hour workload.' Keep max tokens at 512 and temperature at 0.2."},{"title":"Serverless chatbot without account signup","prompt":"Build me a one-off chatbot reply using the Model Access Gateway — no API key, just pay per call in USDC. System prompt: 'You are a friendly customer support agent for a SaaS tool.' User message: 'How do I reset my password?' Temperature 1.0, max 200 tokens."},{"title":"Structured JSON output from LLM","prompt":"Call GPT-6 Luna via the pay-per-call gateway and have it return structured JSON: system prompt 'Respond only with valid JSON', user message 'List the top 3 programming languages for data science with a short reason for each.' Set max_tokens to 1024 and response_format to JSON object mode."}],"resultDescription":"Returns a standard OpenAI-format chat.completion JSON object containing the assistant's reply message, finish reason (e.g. 'stop'), prompt/completion/total token counts, model name, and a unique completion ID. Supports streaming via server-sent events when stream=true. Automatic refund is issued if the model call fails.","failureModes":["Payment rejected or insufficient USDC balance — x402 payment handshake fails before inference runs","Model unavailable or upstream provider error — endpoint returns an error but triggers automatic refund","Invalid messages array (empty or missing required role field) — 400 validation error","max_tokens exceeds 16384 — schema validation error","Temperature outside 0–2 range — validation error","Network timeout on long completions — especially relevant for streaming responses","Malformed response_format object — may cause model to ignore formatting instructions"],"whenToPreferThis":"Choose this endpoint when you need OpenAI-compatible chat completions without an API key or subscription, want to pay micropayments per call in USDC on Base using the x402 protocol, need an automatic refund guarantee if the model fails, or are building an autonomous agent that must self-fund LLM calls via crypto wallet. Prefer it over direct OpenAI or other providers when account-free, pay-per-use stablecoin billing is a hard requirement.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-18T06:47:37.363Z","isFirstParty":false,"canonicalSlug":"model-access-gateway-gpt-6-luna-chat-completions-x402-usdc-cfa9e717"}