# Model Access Gateway – GPT-6.1-Sol Chat Completions (x402, USDC)

> Model Access Gateway – GPT-6.1-Sol 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 2026-10-18).

Runs OpenAI-compatible chat completions using the GPT-6.1-Sol model, billed per-call in USDC on Base via x402 with no API key required.

## Facts

- Endpoint: POST https://modelaccessgateway.com/llm/gpt-6.1-sol?utm_source=zero.xyz
- Price: $0.0014/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/model-access-gateway-gpt-6-1-sol-chat-completions-x402-usdc-5801caac
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_kafYIvyMMqLyERGfZzg1s

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-gpt-6-1-sol-chat-completions-x402-usdc-5801caac -d '<json body>'
```

Example prompt: Ask GPT-6.1-Sol: 'Summarize the pros and cons of solar energy in 3 bullet points' — pay per call in USDC, no API key, up to 512 tokens, temperature 0.7.

## When to prefer this

Choose this endpoint when you need OpenAI-compatible LLM inference with zero account setup, want pay-per-call billing in USDC (no subscription), need automatic refunds on model failure, or are building an autonomous agent that must self-fund inference. Prefer over direct OpenAI API when operating without stored API keys or when using x402 micropayment flows on Base.

## Known failure modes

- Insufficient USDC balance triggers 402 Payment Required with no charge
- Model unavailable or overloaded returns error with automatic refund
- Invalid messages array (missing role or empty array) returns 400 validation error
- max_tokens exceeds 16384 causes schema validation rejection
- Malformed JSON body returns parse error
- Network timeout may leave payment state ambiguous — gateway guarantees refund on failure

## 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 reply message, finish reason (stop, length, tool_calls, etc.), prompt and completion token counts, model identifier, and a unique completion ID. Streaming mode delivers the same content as server-sent events.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Optional: fixed by the route (openai/gpt-6.1-sol)"
  },
  "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": "openai/gpt-6.1-sol",
  "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-gpt-6-1-sol-chat-completions-x402-usdc-5801caac/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)