# RedBTC GPT-5.5 Fixed-Price Chat

> RedBTC GPT-5.5 Fixed-Price Chat is a paid API for AI agents from redbtco.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-12).

Provides a fixed-model GPT-5.5 chat completion endpoint billed at $0.002 USDC per call with no API key required, capped at 700 tokens output for safe autonomous agent use.

## Facts

- Endpoint: POST https://redbtco.com/x402/redbtc/chat/5.5?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/redbtc-gpt-5-5-fixed-price-chat-84909c27
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_aWNOMt0g1r5UJ7Gi-Z5F6

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability redbtc-gpt-5-5-fixed-price-chat-84909c27 -d '<json body>'
```

Example prompt: Ask RedBTC's GPT-5.5 chat route to explain the differences between supervised and unsupervised learning in plain English, keeping the answer under 400 tokens.

## When to prefer this

Choose this endpoint when you need a strong GPT-5.5 model response with predictable per-call USDC billing and no OpenAI API key management, especially in autonomous agent pipelines that require hard output token caps for safety. Prefer it over the sibling gpt-5.4-mini route when output quality matters more than cost minimization. Use it over direct OpenAI access when you want x402 micropayment billing without credential management.

## Known failure modes

- Insufficient USDC balance or failed x402 payment returns a 402 Payment Required error
- Exceeding max_tokens limit of 700 returns a validation error
- Empty or malformed messages array returns a 400 Bad Request
- Upstream GPT-5.5 model unavailability may cause 503 or timeout errors
- Passing model parameter with a different model name is silently overridden to gpt-5.5

## How this service works

Low-cost RedBTC strong chat route. Fixed gpt-5.5, no API key, USDC per call, hard capped for safe autonomous use.

## Output

Returns an OpenAI-compatible chat completion object containing the assistant's generated text, capped at a maximum of 700 output tokens. The model is always GPT-5.5 regardless of any model parameter passed. Each call deducts $0.002 USDC via x402 payment.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Optional. RedBTC forces gpt-5.6-luna on this fixed-price route."
  },
  "messages": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "role",
     "content"
    ],
    "properties": {
     "role": {
      "enum": [
       "system",
       "user",
       "assistant",
       "tool"
      ],
      "type": "string"
     },
     "content": {
      "type": "string"
     }
    }
   },
   "minItems": 1
  },
  "max_tokens": {
   "type": "integer",
   "maximum": 700,
   "minimum": 1
  },
  "temperature": {
   "type": "number",
   "maximum": 2,
   "minimum": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/redbtc-gpt-5-5-fixed-price-chat-84909c27/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from redbtco.com](https://www.zero.xyz/host/redbtco.com/llms.txt)