# Agent402.Tools Premium Responses (LLM Inference via x402)

> Agent402.Tools Premium Responses (LLM Inference via x402) is a paid API for AI agents from agent402.tools, paid per call via x402, $0.5/call, status unknown (last checked 2026-09-15).

Routes a prompt to an allowlisted LLM (OpenAI Responses API-compatible) and streams or returns the completion, paid per-call in USDC via x402 with no API key required.

## Facts

- Endpoint: POST https://agent402.tools/v1/premium/responses
- Price: $0.5/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent402-tools-premium-responses-llm-inference-via-x402-38ab2c63
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_iAB3yv7cdalUE7WxmnuZK

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 agent402-tools-premium-responses-llm-inference-via-x402-38ab2c63 -d '<json body>'
```

Example prompt: Send this message to GPT-4o-mini — 'Summarize the top risks of agentic AI in three bullet points' — and stream the response back to me, paying per call in USDC with no API key.

## When to prefer this

Choose this endpoint when you need LLM inference without signing up for API keys or managing subscriptions — ideal for AI agents that authenticate via a crypto wallet and pay per call in USDC using the x402 protocol. Prefer it over OpenAI or OpenRouter direct when you want wallet-as-identity, zero-signup access to 500+ tools and models, or when your agent stack is already x402-native. It is especially valuable for multi-model routing (OpenRouter naming), controllable reasoning effort, zero-data-retention requirements, and streaming completions in agentic pipelines.

## Known failure modes

- Payment not included or insufficient USDC — 402 Payment Required returned
- Model ID not on allowlist for the caller's tier — rejected with model error
- Inner dimension mismatch in tool call parameters — function_call validation error
- max_output_tokens clamped to tier cap silently — output may be truncated
- Zero-data-retention filter excludes requested model — provider unavailable
- Malformed input array (missing role or content) — 400 Bad Request
- Streaming connection dropped mid-response — partial SSE stream, no completed event

## How this service works

OpenAI Responses API over x402 - point the OpenAI SDK's responses.create() (or the OpenAI Agents SDK) at base_url https://agent402.tools/v1/premium and pay $0.50 per call in USDC, no API key, no signup. Same models, caps and price as this tier's /chat/completions route; any model here is served through the Responses wire.

## Output

Returns an OpenAI Responses API-compatible JSON object containing the assistant's output message(s), the model used, input/output/total token counts, a response ID, and a completion status. In streaming mode, delivers SSE events (response.created through response.completed) with incremental content deltas.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "zdr": {
   "type": "boolean",
   "description": "Optional - zero-data-retention providers only"
  },
  "text": {
   "type": "object",
   "description": "Optional {format: {type: \"text\"|\"json_schema\"|\"json_object\", ...}}"
  },
  "input": {
   "description": "A string, or an array of input items ({role, content} messages with input_text / input_image parts, function_call, function_call_output)"
  },
  "model": {
   "type": "string",
   "description": "Model id (OpenRouter naming) - allowlisted per tier; omit (or \"auto\") on the auto tier"
  },
  "tools": {
   "type": "array",
   "description": "Optional function tools ({type:\"function\", name, parameters}); server-side tools are not served"
  },
  "stream": {
   "type": "boolean",
   "description": "Responses SSE events (response.created … response.completed)"
  },
  "reasoning": {
   "type": "object",
   "description": "Optional {effort: \"none\"|\"minimal\"|\"low\"|\"medium\"|\"high\"|\"xhigh\"|\"max\"} - reasoning tokens count against max_output_tokens"
  },
  "instructions": {
   "type": "string",
   "description": "Optional system/developer instructions"
  },
  "max_output_tokens": {
   "type": "integer",
   "description": "Optional output cap (clamped to the tier cap)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "resp_…",
  "model": "openai/gpt-4o-mini",
  "usage": {
   "input_tokens": 14,
   "total_tokens": 32,
   "output_tokens": 18
  },
  "object": "response",
  "output": [
   {
    "id": "msg_…",
    "role": "assistant",
    "type": "message",
    "status": "completed",
    "content": [
     {
      "text": "x402 is an HTTP-native way for agents to pay per request with USDC.",
      "type": "output_text",
      "annotations": []
     }
    ]
   }
  ],
  "status": "completed"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent402-tools-premium-responses-llm-inference-via-x402-38ab2c63/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)