{"uid":"cap_MwUy-1yLfTpeEUzAPZbQo","slug":"model-access-gateway-gemini-3-1-pro-chat-completions-x402-usdc-ccc1a251","name":"Model Access Gateway – Gemini 3.1 Pro 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/gemini-3.1-pro?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"model":{"type":"string","description":"Optional: fixed by the route (google/gemini-3.1-pro)"},"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":"google/gemini-3.1-pro","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_NYXIHzrXUCXWDe_kDyz1e","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 Google Gemini 3.1 Pro, billed per call in USDC on Base via x402 — no API key or account required.","exampleAgentPrompt":"Ask Gemini 3.1 Pro to write a detailed product description for a new ergonomic office chair aimed at remote workers, keeping the tone professional and the response under 300 words — pay for it with USDC on Base, no API key needed.","exampleUseCases":[{"title":"Crypto-native agent reasoning step","prompt":"I need you to use Gemini 3.1 Pro to reason through this multi-step math word problem and show your work — pay per call using USDC so I don't have to sign up for anything."},{"title":"Structured JSON extraction from text","prompt":"Send this customer support ticket to Gemini 3.1 Pro and ask it to extract the issue category, urgency, and suggested resolution as JSON — use response_format JSON mode and keep max_tokens at 512."},{"title":"Streaming creative writing assistant","prompt":"Have Gemini 3.1 Pro write me the opening chapter of a sci-fi short story about a colony on Europa, streaming the output as it's generated, and charge my wallet in USDC for the call."}],"resultDescription":"Returns an OpenAI-compatible chat.completion JSON object containing the assistant's message content, finish reason (e.g. 'stop'), token usage breakdown (prompt, completion, total), model identifier ('google/gemini-3.1-pro'), and a unique completion ID. Streaming mode returns server-sent events instead.","failureModes":["Model failure triggers automatic USDC refund to the caller's wallet","Invalid or missing messages array returns a 400 validation error","Payment insufficient or x402 handshake failure prevents inference from starting","max_tokens exceeding 16384 returns a schema validation error","Network timeout or model unavailability may return a 5xx error with no charge"],"whenToPreferThis":"Choose this endpoint when you need Gemini 3.1 Pro specifically, want OpenAI-compatible request/response format, require no account or API key setup, and prefer crypto-native micropayments in USDC via x402 rather than monthly subscriptions. Ideal for autonomous agents that need to pay programmatically per inference call with automatic refund guarantees on failure.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-18T06:35:16.971Z","isFirstParty":false,"canonicalSlug":"model-access-gateway-gemini-3-1-pro-chat-completions-x402-usdc-ccc1a251"}