# Model Access Gateway – Claude Haiku 5.5 via x402

> Model Access Gateway – Claude Haiku 5.5 via x402 is a paid API for AI agents from agent402-arb.rosariovitale0096.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-17).

Runs OpenAI-compatible chat completions against Anthropic Claude Haiku 5.5, billed per request in USDC on Base via x402 with no account or API key required.

## Facts

- Endpoint: POST https://agent402-arb.rosariovitale0096.workers.dev/llm/claude-haiku-5.5?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/model-access-gateway-claude-haiku-5-5-via-x402-caa5612f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Z4pEG3Sevd7JT6k3XlpCM

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-haiku-5-5-via-x402-caa5612f -d '<json body>'
```

Example prompt: Send this message to Claude Haiku 5.5 and give me the reply: 'Summarize the key differences between REST and GraphQL in three bullet points.' Pay for it with USDC on Base.

## When to prefer this

Choose this endpoint when you need to call Claude Haiku 5.5 with no prior account setup, no API key management, and want to pay strictly per-request in USDC on Base via x402 — ideal for autonomous agents, onchain apps, or serverless workflows that need crypto-native LLM access with an OpenAI-compatible interface.

## Known failure modes

- 402 Payment Required if USDC payment header is missing or insufficient
- Invalid or malformed request body returns 400
- Model unavailable or upstream API error returns 502 or 503
- Insufficient USDC balance on Base causes payment failure
- Rate limiting by the underlying workers.dev infrastructure

## 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-style chat.completion JSON object containing the assistant's message text, model name (anthropic/claude-haiku-5.5), prompt and completion token counts, finish reason, and a completion ID — identical in shape to the OpenAI Chat Completions API response.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Optional: fixed by the route (anthropic/claude-haiku-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-haiku-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-haiku-5-5-via-x402-caa5612f/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)