# Model Access Gateway — Claude Haiku 5.5 Chat Completions (x402, USDC)

> Model Access Gateway — Claude Haiku 5.5 Chat Completions (x402, USDC) is a paid API for AI agents from modelaccessgateway.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-18).

Runs an OpenAI-compatible chat completion request against Claude Haiku 5.5 (Anthropic), paid per call in USDC on Base via x402 — no API key or account required.

## Facts

- Endpoint: POST https://modelaccessgateway.com/llm/claude-haiku-5.5?utm_source=zero.xyz
- Price: $0.001/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-haiku-5-5-chat-completions-x402-usdc-f641585c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_QzGnJioJSjZ6Dr7apqGOr

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-chat-completions-x402-usdc-f641585c -d '<json body>'
```

Example prompt: Ask Claude Haiku 5.5 to summarize the following text in three bullet points: 'Quantum computing leverages superposition and entanglement to perform calculations exponentially faster than classical computers, with implications for cryptography, drug discovery, and optimization problems.' Keep it under 200 tokens and use a temperature of 0.3.

## When to prefer this

Choose this endpoint when you need Claude Haiku 5.5 specifically, want zero-setup anonymous access (no API key, no account), are operating from a crypto wallet or x402-enabled agent, and want automatic refunds on failure. Prefer it over raw Anthropic API when you cannot or prefer not to manage API credentials, or when your agent architecture already uses x402 micropayments on Base. It is cost-effective at $0.001/call for high-throughput, low-latency tasks like classification, summarization, and short-form generation.

## Known failure modes

- Insufficient USDC balance — payment rejected before inference runs
- Model unavailable or upstream Anthropic error — triggers automatic refund
- Invalid messages array (empty or missing required 'role' field) — validation error
- max_tokens out of range (must be 1–16384) — rejected with parameter error
- Stream response interrupted after payment but before completion — partial SSE stream

## 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 a standard OpenAI-format chat.completion JSON object containing the assistant's reply text, finish_reason (e.g. 'stop'), prompt/completion/total token counts, a completion ID, model name, and created timestamp. If streaming is enabled, server-sent events are returned after payment is confirmed. If the model call fails, an automatic USDC refund is issued.

## 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-chat-completions-x402-usdc-f641585c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from modelaccessgateway.com](https://www.zero.xyz/host/modelaccessgateway.com/llms.txt)