# Model Access Gateway – Claude Opus 4.5 via x402

> Model Access Gateway – Claude Opus 4.5 via x402 is a paid API for AI agents from agent402-arb.rosariovitale0096.workers.dev, paid per call via x402, $0.0014/call, status unknown (last checked 2026-10-18).

Proxies OpenAI-compatible chat completion requests to Anthropic Claude Opus 4.5, billed per request in USDC on Base via x402 protocol — no API key required.

## Facts

- Endpoint: POST https://agent402-arb.rosariovitale0096.workers.dev/llm/claude-opus-5.5?utm_source=zero.xyz
- Price: $0.0014/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/model-access-gateway-claude-opus-4-5-via-x402-4f0fccd6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5_KJZATMtRbrNvUBH0y9l

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 model-access-gateway-claude-opus-4-5-via-x402-4f0fccd6 -d '<json body>'
```

Example prompt: Send this conversation to Claude Opus 4.5 and get a response: the system prompt says 'You are a helpful assistant' and the user asked 'What is the capital of France?' — pay per request using USDC on Base.

## When to prefer this

Choose this endpoint when you need Claude Opus 4.5 specifically (Anthropic's highest-capability model) without holding an Anthropic API key, and you want to pay per request in USDC on Base using the x402 protocol. It is ideal for autonomous agents operating in crypto-native environments, one-off inference tasks, or multi-model pipelines where account management overhead is undesirable. Prefer alternatives if you need streaming responses, batch inference at scale, or are already holding Anthropic or OpenAI API keys with volume discounts.

## Known failure modes

- Payment not provided or insufficient USDC balance — gateway returns HTTP 402 Payment Required
- Malformed request body (missing required 'input' field or invalid bodyType) — returns 400 Bad Request
- Model temporarily unavailable upstream at Anthropic — returns 503 or upstream error
- Rate limiting on the worker — returns 429 Too Many Requests
- Invalid or expired x402 payment token — returns 402 with rejection details

## How this service works

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.

## Output

Returns an OpenAI-compatible chat.completion JSON object including the assistant's message content, model name (anthropic/claude-opus-5.5), token usage (prompt, completion, total), finish reason, and a completion ID and timestamp. The response mirrors the standard OpenAI /v1/chat/completions format for easy drop-in integration.

## Request schema (JSON Schema)

```json
{
 "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"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "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
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/model-access-gateway-claude-opus-4-5-via-x402-4f0fccd6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402-arb.rosariovitale0096.workers.dev](https://www.zero.xyz/host/agent402-arb.rosariovitale0096.workers.dev/llms.txt)