# Model Access Gateway – Gemini 3.1 Pro via x402

> Model Access Gateway – Gemini 3.1 Pro 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 2026-10-17).

Runs OpenAI-compatible chat completions against Google Gemini 3.1 Pro, 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/gemini-3.1-pro?utm_source=zero.xyz
- Price: $0.0014/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-gemini-3-1-pro-via-x402-e4971a56
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AINSGMiMe0nF0cN1BGD0M

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-gemini-3-1-pro-via-x402-e4971a56 -d '<json body>'
```

Example prompt: Send the message 'Summarize the key differences between transformer and diffusion models in 3 bullet points' to Gemini 3.1 Pro and give me back the response — pay for it per-request in USDC, no API key needed.

## When to prefer this

Choose this endpoint when you need Gemini 3.1 Pro inference with zero account setup — ideal for autonomous agents or dApps that want to pay per-call in USDC via x402 on Base rather than managing API keys or subscriptions. Prefer it over direct Google AI Studio when you need a crypto-native, OpenAI-compatible interface with no monthly commitment.

## Known failure modes

- 402 Payment Required if x402 USDC payment on Base is not attached or insufficient
- Model name not found if the path is wrong or model unavailable
- Malformed request body returns 400 if required fields (messages, etc.) are missing
- Rate limiting or worker timeout on very long prompts
- Incorrect OpenAI-compat schema (e.g. missing 'messages' array) causes parse error
- Network errors from Cloudflare Workers edge node

## 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 content, the model name (google/gemini-3.1-pro), token usage breakdown (prompt, completion, total), finish reason, and a unique completion ID and timestamp.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Optional: fixed by the route (google/gemini-3.1-pro)"
  },
  "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": "google/gemini-3.1-pro",
  "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-gemini-3-1-pro-via-x402-e4971a56/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)