Skill: API investigation

Bundled execution of the API investigation workflow — Point at an unknown API endpoint and figure out how to use it: auth scheme, content type, version, rate limits, OpenAPI/Swagger spec discovery, and JSON response structure. The deterministic recon workflow before writing a single line of integration code. One x402 payment runs 7 underlying tools (url-parse, http-check, http-headers, extract, html-links, json-format, json-query); partial-success per step.

Input

Field	Type	Description
endpoint *	string	API URL to investigate (e.g. https://api.example.com/v1/users)

Example output

{
  "pack": "api-investigation",
  "args": {
    "endpoint": "https://api.example.com/v1/users"
  },
  "steps": [
    {
      "slug": "url-parse",
      "ok": true,
      "result": {}
    },
    {
      "slug": "http-check",
      "ok": true,
      "result": {}
    },
    {
      "slug": "http-headers",
      "ok": true,
      "result": {}
    },
    {
      "slug": "extract",
      "ok": true,
      "result": {}
    },
    {
      "slug": "html-links",
      "ok": true,
      "result": {}
    },
    {
      "slug": "json-format",
      "ok": true,
      "result": {}
    },
    {
      "slug": "json-query",
      "ok": true,
      "result": {}
    }
  ],
  "summary": "7/7 steps succeeded"
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/skill/api-investigation \
  -H "Content-Type: application/json" \
  -d '{"endpoint":"https://api.example.com/v1/users"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

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();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/skill/api-investigation", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "endpoint": "https://api.example.com/v1/users"
  }),
});

Wallet-only. This tool reaches the network/browser/storage, so it is paid in USDC via x402 (no proof-of-work tier).

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