# Model Access Gateway – Claude Opus 5 Chat Completions (x402, USDC)

> Model Access Gateway – Claude Opus 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 OpenAI-compatible chat completions against Claude Opus 5 via a pay-per-call API billed in USDC on Base using the x402 protocol — no account or API key required.

## Facts

- Endpoint: POST https://modelaccessgateway.com/llm/claude-opus-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-opus-5-chat-completions-x402-usdc-6cc59e0b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1x7CFNJjBPV1U03HYzEPv

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-5-chat-completions-x402-usdc-6cc59e0b -d '<json body>'
```

Example prompt: Ask Claude Opus 5 to analyze this legal contract and summarize the key obligations and risks — stream the response back, use up to 8000 tokens, and keep temperature at 0.2 for precision.

## When to prefer this

Choose this endpoint when you need Claude Opus 5 specifically (Anthropic's most capable model) and want pay-per-call pricing in USDC with no account signup, API key management, or subscription. Ideal for autonomous agents that need to make one-off LLM calls, developers prototyping without committing to a provider, or workflows that require the automatic refund guarantee on model failure. Prefer over direct Anthropic API when you need anonymous/keyless access or are already operating in a crypto-native payment environment using x402.

## Known failure modes

- Insufficient USDC balance — payment rejected before inference begins
- Model unavailable or overloaded — automatic refund issued, no charge
- Invalid messages array (missing required role field) — 422 validation error
- max_tokens exceeds 16384 limit — request rejected
- Temperature outside 0–2 range — validation error
- Network timeout on streaming response — partial output, no refund guarantee

## 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 containing the assistant's message content, finish reason (e.g. 'stop'), token usage breakdown (prompt, completion, total), model name, completion ID, and creation timestamp. Streaming mode delivers server-sent events incrementally.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Optional: fixed by the route (anthropic/claude-opus-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",
  "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-5-chat-completions-x402-usdc-6cc59e0b/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)