# Model Access Gateway – Claude Sonnet 5 Chat Completions (x402/USDC)

> Model Access Gateway – Claude Sonnet 5 Chat Completions (x402/USDC) is a paid API for AI agents from modelaccessgateway.com, paid per call via x402, $0.0014/call, status unknown (last checked 2026-10-16).

Runs an OpenAI-compatible chat completion against Anthropic's Claude Sonnet 5, billed per-call in USDC on Base via x402 — no account or API key required.

## Facts

- Endpoint: POST https://modelaccessgateway.com/llm/claude-sonnet-5?utm_source=zero.xyz
- Price: $0.0014/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/model-access-gateway-claude-sonnet-5-chat-completions-x402-usdc-ae23d149
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qJh2N51wmceGmfUrqn5hh

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-sonnet-5-chat-completions-x402-usdc-ae23d149 -d '<json body>'
```

Example prompt: Ask Claude Sonnet 5 to summarize the following text for me — pay per call in USDC so I don't need to set up an API key: 'Quantum computing leverages superposition and entanglement to perform calculations exponentially faster than classical computers for certain problem classes.'

## When to prefer this

Choose this endpoint when you need Claude Sonnet 5 specifically, want to avoid creating an Anthropic account or managing API keys, prefer paying per-call in USDC on Base (ideal for autonomous agents with crypto wallets), or need the automatic refund guarantee on model failure. It is the best fit for agentic workflows using the x402 payment protocol and for one-off or low-volume Claude calls where a subscription is wasteful.

## Known failure modes

- Model inference failure triggers automatic USDC refund to caller
- Malformed messages array (missing required 'role') returns 400 validation error
- max_tokens exceeding 16384 returns schema validation error
- Insufficient USDC balance on Base causes x402 payment rejection before inference
- Network timeout on Base blockchain payment confirmation delays or fails the call
- Unsupported content type in messages array may cause 422 error

## 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-format chat.completion JSON object containing the assistant's message content, finish reason (e.g. 'stop'), token usage breakdown (prompt, completion, total tokens), model name, a unique completion ID, and a created timestamp. Streaming mode delivers the same content as server-sent events after payment is confirmed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Optional: fixed by the route (anthropic/claude-sonnet-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-sonnet-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-sonnet-5-chat-completions-x402-usdc-ae23d149/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)