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Agent402 Pro Responses - Pay-Per-Call AI Completions via x402
x402
Agent402 Pro Responses - Pay-Per-Call AI Completions via x402 is a paid API for AI agents from agent402.tools, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).
Runs AI chat/completion requests through a pay-per-call OpenAI Responses-compatible endpoint, billed at $0.10 USDC per call via x402 micropayment protocol — no API key required.
Price / call$0.1
Success—
StatusUnknown
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/pro and pay $0.10 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 reply text, the model used, input/output/total token counts, a response ID, and completion status. When streaming is enabled, returns SSE events (response.created through response.completed) with incremental content chunks.
Example use cases
Wallet-authenticated agent reasoning
“I want my agent to ask gpt-4o: 'What are the top 5 risks of deploying autonomous AI agents in financial markets?' — pay for it with my USDC wallet, no signup, and return the full answer.”
Structured JSON output from AI model
“Call an AI model — use gpt-4o-mini — with the instruction 'Extract the company name, founding year, and CEO from the following text' and enforce a JSON schema output. The input text is: 'OpenAI was founded in 2015 and is currently led by Sam Altman.'”
AI reasoning with high effort for complex task
“Send this problem to the best reasoning model available on Agent402: 'Prove that the square root of 2 is irrational.' Use high reasoning effort and return the step-by-step solution.”
Technical details
Endpoint
POSThttps://agent402.tools/v1/pro/responsesWhen to prefer
Choose this endpoint when you need OpenAI-compatible LLM completions without managing API keys or subscriptions — ideal for AI agents that authenticate via crypto wallet using x402 or MPP micropayments. Prefer it over direct OpenAI/Anthropic APIs when you want pay-per-call billing in USDC, anonymous/wallet-based identity, or access to 500+ tool-augmented models through a single endpoint. Also prefer when building agent pipelines that need on-chain payment trails or zero-data-retention options.
Side effects
- Payment not included or insufficient USDC — returns HTTP 402 with payment details
- Model ID not allowlisted for the current tier — returns error indicating invalid model
- Input exceeds max_output_tokens cap for the tier — tokens clamped or rejected
- Malformed input array (invalid role/content structure) — returns validation error
- Network timeout on long reasoning requests — partial SSE stream may be cut off
- Zero-data-retention filter applied but no ZDR-compliant provider available — returns provider error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| zdr | boolean | Optional - zero-data-retention providers only |
| text | object | Optional {format: {type: "text"|"json_schema"|"json_object", ...}} |
| input | — | A string, or an array of input items ({role, content} messages with input_text / input_image parts, function_call, function_call_output) |
| model | string | Model id (OpenRouter naming) - allowlisted per tier; omit (or "auto") on the auto tier |
| tools | array | Optional function tools ({type:"function", name, parameters}); server-side tools are not served |
| stream | boolean | Responses SSE events (response.created … response.completed) |
| reasoning | object | Optional {effort: "none"|"minimal"|"low"|"medium"|"high"|"xhigh"|"max"} - reasoning tokens count against max_output_tokens |
| instructions | string | Optional system/developer instructions |
| max_output_tokens | integer | Optional output cap (clamped to the tier cap) |
Output
Schema · Response
{
"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"
}
}Tags
x402
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