# FarOut LLM Inference – Gemini 3.1 Pro via x402

> FarOut LLM Inference – Gemini 3.1 Pro via x402 is a paid API for AI agents from farouter.tech, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Runs a Gemini 3.1 Pro chat completion request, billed per-call in USDC over the x402 protocol with no API key or account required.

## Facts

- Endpoint: POST https://farouter.tech/v1/models/gemini-3.1-pro/chat/completions
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/farout-llm-inference-gemini-3-1-pro-via-x402-e63924a3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Cos20Wn6iFhYUm3sxeWVU

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 farout-llm-inference-gemini-3-1-pro-via-x402-e63924a3 -d '<json body>'
```

Example prompt: Use FarOut to call Gemini 3.1 Pro and answer this: 'Explain the difference between Proof of Work and Proof of Stake in three sentences.' Set max_tokens to 200 and temperature to 0.7, paying per request with USDC on Base.

## When to prefer this

Choose this endpoint when an autonomous agent needs frontier LLM inference (specifically Gemini 3.1 Pro) without API key management or account setup, and can pay per-call in USDC via the x402 protocol. Ideal for agent-to-agent workflows, ephemeral agents, or scenarios where prepaid credits are impractical. Prefer over standard Google AI API when crypto-native payment rails and zero-signup access matter more than volume discounts.

## Known failure modes

- Payment failure or insufficient USDC balance on Base — x402 payment rejected
- Invalid model ID not matching available models — 400 or 422 error
- messages array empty or missing required role/content fields — validation error
- max_tokens set too high for model context window — truncation or error
- Rate limiting or upstream Gemini API unavailability — 503 or timeout
- Malformed JSON body — 400 bad request

## How this service works

Fixed-price chat completions for gemini-3.1-pro on FarOut: flat $0.001 per call (includes up to 4,000 input + 1,000 output tokens). Rate: $0.072/1M input tokens, $0.432/1M output tokens. Pay with USDC on Base using x402. No API key, no account, no prepaid balance.

## Output

Returns an OpenAI-compatible JSON object with a choices array containing the assistant's message text and finish reason, plus a usage object with prompt_tokens and completion_tokens counts.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Model id from GET /v1/models, e.g. glm-5.3. No provider prefix."
  },
  "stream": {
   "type": "boolean",
   "description": "SSE streaming."
  },
  "messages": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "role",
     "content"
    ],
    "properties": {
     "role": {
      "enum": [
       "system",
       "developer",
       "user",
       "assistant",
       "tool"
      ],
      "type": "string"
     },
     "content": {}
    },
    "additionalProperties": true
   },
   "minItems": 1,
   "description": "Chat messages, [OI]-compatible {role, content}."
  },
  "max_tokens": {
   "type": "integer",
   "minimum": 1,
   "description": "Output token budget. Drives the quote directly."
  },
  "temperature": {
   "type": "number",
   "maximum": 2,
   "minimum": 0,
   "description": "Sampling temperature."
  },
  "max_completion_tokens": {
   "type": "integer",
   "minimum": 1,
   "description": "Alias of max_tokens (gpt-5.x models)."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "usage": {
   "prompt_tokens": 6,
   "completion_tokens": 8
  },
  "choices": [
   {
    "message": {
     "role": "assistant",
     "content": "Hello! How can I help?"
    },
    "finish_reason": "stop"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/farout-llm-inference-gemini-3-1-pro-via-x402-e63924a3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from farouter.tech](https://www.zero.xyz/host/farouter.tech/llms.txt)