{"uid":"cap_vhpkmA-vhlOWsgE7obKks","slug":"model-access-gateway-claude-opus-5-5-chat-completions-x402-usdc-58eb6227","name":"Model Access Gateway – Claude Opus 5.5 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/claude-opus-5.5?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"model":{"type":"string","description":"Optional: fixed by the route (anthropic/claude-opus-5.5)"},"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":"anthropic/claude-opus-5.5","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_-SSHEt0sTNg7uKgVgSbWz","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 a single Claude Opus 5.5 chat completion request via an OpenAI-compatible API, paid per-call in USDC on Base using x402 — no account or API key required.","exampleAgentPrompt":"Ask Claude Opus 5.5 to write me a detailed technical explanation of how transformers work — use the Model Access Gateway pay-per-call endpoint so we don't need an API key, stream the response, and keep it under 2000 tokens.","exampleUseCases":[{"title":"Autonomous agent single-shot reasoning","prompt":"Have Claude Opus 5.5 analyze this business plan summary and list the top 3 risks — pay per call through Model Access Gateway so we skip the API key setup, and keep the reply under 1000 tokens."},{"title":"No-account code review on demand","prompt":"Send this Python function to Claude Opus 5.5 via Model Access Gateway and ask it to find bugs and suggest improvements — no subscription needed, just pay the USDC fee for this one call."},{"title":"Streamed creative writing generation","prompt":"Use Claude Opus 5.5 on Model Access Gateway to write a short sci-fi story opening based on this premise: 'a botanist discovers plants that transmit memories' — stream the response and limit it to 800 tokens."}],"resultDescription":"Returns an OpenAI-compatible chat.completion JSON object containing the assistant's message content, role, finish reason, a unique completion ID, the model name (anthropic/claude-opus-5.5), creation timestamp, and token usage breakdown (prompt, completion, total). When streaming is enabled, responses arrive as server-sent events in the same schema.","failureModes":["Payment failure or insufficient USDC balance — x402 payment rejected, no completion returned but automatic refund triggered","Model unavailable or overloaded — upstream Anthropic API error, refund issued automatically","Invalid messages array (empty or malformed) — 400 validation error","max_tokens exceeds 16384 — 400 schema validation error","Temperature out of range (0–2) — 400 validation error","Network timeout during streaming — partial SSE stream, no refund guarantee","Unsupported role in messages — 400 error referencing enum constraint"],"whenToPreferThis":"Choose this endpoint when you need Claude Opus 5.5 specifically (Anthropic's most capable model in this gateway) without an Anthropic API account, when operating as an autonomous agent that can settle payments in USDC on Base via x402, or when you want pay-per-call pricing with automatic refunds on failure rather than a monthly subscription. Prefer over direct Anthropic API when no API key management is acceptable, or when building agentic workflows that need trustless, on-chain payment settlement.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-18T06:35:21.744Z","isFirstParty":false,"canonicalSlug":"model-access-gateway-claude-opus-5-5-chat-completions-x402-usdc-58eb6227"}