# Model Access Gateway – Gemini 4 Argon Chat Completions (x402 USDC)

> Model Access Gateway – Gemini 4 Argon 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 2026-10-16).

Runs OpenAI-compatible chat completions against Google's Gemini 4 Argon model, billed per call in USDC on Base via the x402 protocol — no account or API key required.

## Facts

- Endpoint: POST https://modelaccessgateway.com/llm/gemini-4-argon?utm_source=zero.xyz
- Price: $0.001/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-gemini-4-argon-chat-completions-x402-usdc-afe695d8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Tnklxa1hIGVxrAHfFeJ2O

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-4-argon-chat-completions-x402-usdc-afe695d8 -d '<json body>'
```

Example prompt: Ask Gemini 4 Argon to summarize the following meeting notes in 3 bullet points, allow up to 512 tokens, and use a temperature of 0.3: [paste notes here].

## When to prefer this

Choose this endpoint when you need Gemini 4 Argon specifically and want to avoid managing API keys or Google Cloud credentials. It is ideal for autonomous agents that hold USDC on Base and need pay-as-you-go LLM inference with no subscription. Prefer it over direct Google AI Studio when you want OpenAI SDK compatibility, crypto-native payment, and automatic failure refunds in a single call.

## Known failure modes

- Model failure triggers automatic USDC refund — no partial charge
- Insufficient USDC balance causes payment rejection before inference runs
- Invalid messages array (missing required 'role') returns a 422 validation error
- max_tokens exceeding 16384 is rejected at schema validation
- Stream requested but client doesn't handle SSE — response may appear garbled
- Temperature outside 0–2 range returns a validation 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-compatible chat.completion JSON object containing the assistant's response message, finish reason, token usage (prompt, completion, total), model identifier, and a unique completion ID. On streaming, returns server-sent events. If the model fails, the call is automatically refunded.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Optional: fixed by the route (google/gemini-4-argon)"
  },
  "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-4-argon",
  "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-4-argon-chat-completions-x402-usdc-afe695d8/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)