Image generation (Premium)

Generate a larger image from a text prompt using GPT Image 2 (medium quality): 1536x1024 landscape by default, 1024x1536 portrait or 1024x1024 square via orientation. Send POST /api/image-gen-premium with the required field prompt and pay $0.15 per call over x402 with USDC on an EVM chain or MPP. It returns a JSON object with model, provider, quality, size, image and 1 more.

No API key needed; pay per call via x402. Returns base64 PNG. Prompt capped at 4000 chars. A render takes 25 to 50 s; use a client timeout of at least 75 s. Takes up to 75 seconds to answer: send the paid call with "Prefer: respond-async" to get a job link at once and collect the answer from it (payment still settles only on a delivered result), or with "Prefer: wait=75" and keep the connection open for at least 105 seconds, because a client that disconnects first loses the answer. A paid call with neither header is answered 400 before any payment is taken.

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Parameters

Example request

curl -i -X POST https://agent402.tools/api/image-gen-premium \
  -H "Content-Type: application/json" \
  -d '{"prompt":"A single red apple on a white background"}'

Without payment this returns HTTP 402 Payment Required with the exact price for image-gen-premium; any x402 v2 or MPP client pays it and retries.

Example response

{
  "model": "gpt-image-2",
  "provider": "openai",
  "quality": "medium",
  "size": "1536x1024",
  "image": "<base64-encoded PNG>",
  "revised_prompt": "A single red apple on a white background"
}

From an MCP client

catalog.call {
  "slug": "image-gen-premium",
  "params": {
    "prompt": "A single red apple on a white background"
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for image-gen-premium; the stdio package pays it from a wallet or from an AGENT402_CREDITS_KEY issued earlier. Local install: npx -y [email protected].

Errors and behavior

• prompt is required. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example, so the caller can correct it.
• A paid call that ends in any status of 400 or above is not charged over x402, MPP or a prepaid credits key: settlement runs after the tool and only on a successful response.
• Wallet-only: this tool runs a model, so it has no proof-of-work tier. A prepaid card-credits key issued earlier (Authorization: Bearer a402_...) also pays it.
• Model-backed: the answer is generated by a model, so the same input can produce a different result.
• Long-running: payment settles after the work finishes, so x402 is offered on EVM chains only and MPP on Base or Celo; Tempo is not offered.
• Usually answers in about 40 seconds and takes up to 75 seconds. Send the paid call with Prefer: respond-async to get 202 and a job link at once, then poll GET /api/jobs/{id} for its stage, progress and ETA until it has the answer; payment still settles only when the answer is ready. To wait on the connection instead, send Prefer: wait=75 and keep it open that long. A paid call with neither header is answered 400 before any payment is taken.
• A GET or HEAD to /api/image-gen-premium returns the same 402 quote, so the price can be read without a body.
• An Idempotency-Key header makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
client.setSpendControls?.({ maxAmountPerPayment: "$0.15" }); // refuse any quote above this tool's price
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/image-gen-premium", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "prompt": "A single red apple on a white background"
  }),
});

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