OpenAI GPT-5.5 Long Context Chat Completions (via mm.family x402)

x402

OpenAI GPT-5.5 Long Context Chat Completions (via mm.family x402) is a paid API for AI agents from openai.mm.family, paid per call via x402, $0.001682/call, status unknown (last checked 2026-10-02).

Provides OpenAI GPT-5.5 chat completions for prompts exceeding 272K input tokens, billed per call in USDC via the x402 payment protocol with configurable quality tiers.

Price / call$0.001682

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StatusUnknown

How this service works

gpt-5.5-long: OpenAI GPT 5.5 (>272K input tokens) chat completions, paid per call in USDC. Per 1M tokens in/out: Flex (default) 5.0/22.5, Standard 10.0/45.0; pick with service_tier. Plus $0.0005 (Base) or $0.0005 (Solana) per call; the quote charges input plus 10% of max_tokens. Levels: none, low, medium, high, xhigh (model gpt-5.5-long:<level>). Empty answers are free. Rates: https://openai.mm.family/x402/pricing

Output

Returns a JSON chat completion object matching the OpenAI API format, including the assistant's message content, role, finish reason, token usage breakdown (prompt, completion, total), model name, and service tier used. Empty responses when the model produces no output are free of charge.

Example use cases

Analyze a book-length codebase

“I've got the full source code of a large open-source project — it's well over 300K tokens. Feed it all to GPT-5.5 and ask it to explain the overall architecture and highlight any security vulnerabilities. Use the standard tier for best quality and allow up to 4000 output tokens.”

Summarize lengthy legal discovery documents

“I have 500 pages of legal deposition transcripts. Send them all to GPT-5.5 and ask it to produce a structured summary of key admissions and contradictions, using the flex tier and capping output at 3000 tokens.”

Multi-turn research assistant with large context

“I want to have a detailed conversation with GPT-5.5 where I've loaded in 50 academic papers as context. Start with the question: 'What are the most contested findings across these papers and where do they agree?' Use the high reasoning level and set max_tokens to 2500.”

Technical details

Endpoint

POSThttps://openai.mm.family/x402/v1/models/gpt-5.5-long/chat/completions?utm_source=zero.xyz

When to prefer

Choose this endpoint when you need GPT-5.5 specifically for prompts exceeding 272K input tokens (book-length documents, large codebases, lengthy transcripts) and want to pay per call in USDC without a direct OpenAI subscription. Prefer it over the standard gpt-5.5 endpoint when your input context is very large, and use the flex tier for cost savings or standard tier for priority throughput. The x402 crypto-native payment model makes it ideal for autonomous agents that manage their own wallets.

Side effects

Insufficient USDC balance or x402 payment failure results in 402 Payment Required
Prompt exceeds model context window limits even for long variant
max_tokens set too low causes truncated or empty responses
Invalid service_tier enum value causes request rejection
Streaming errors if network connection drops mid-response
Rate limiting if too many concurrent calls are made

Input

Schema · Request body

Field	Type	Description
model	string
tools	array
stream	boolean
messages	array
max_tokens	integer
service_tier	string
response_format	object
reasoning_effort	string

Output

Schema · Response

{
  "type": "json",
  "example": {
    "id": "chatcmpl-x",
    "model": "gpt-5.5-long",
    "usage": {
      "total_tokens": 9,
      "prompt_tokens": 8,
      "completion_tokens": 1
    },
    "object": "chat.completion",
    "choices": [
      {
        "index": 0,
        "message": {
          "role": "assistant",
          "content": "Hello",
          "refusal": null
        },
        "finish_reason": "stop"
      }
    ],
    "service_tier": "flex"
  }
}

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