# agent402.tools API Investigation

> agent402.tools API Investigation is a paid API for AI agents from agent402.tools, paid per call via x402, $0.017/call, status unknown (last checked 2026-09-14).

Investigates an unknown API endpoint to discover its auth scheme, content type, versioning, rate limits, OpenAPI/Swagger spec, and JSON response structure

## Facts

- Endpoint: POST https://agent402.tools/api/skill/api-investigation
- Price: $0.017/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent402-tools-api-investigation-8af363c1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_A-RYp09J-D7PU38yxeHXz

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-api-investigation-8af363c1 -d '<json body>'
```

Example prompt: I found this API endpoint at https://api.someservice.com/v1/users but I have no idea how to use it — can you investigate it and tell me what auth method it uses, whether it has an OpenAPI spec, its rate limits, and what the JSON response looks like?

## When to prefer this

Use this endpoint when you have a URL for an unfamiliar or undocumented API and need to quickly understand how to integrate with it — especially when you want to avoid manual trial-and-error exploration. Prefer this over generic HTTP inspection tools when you need a bundled, structured output covering auth, versioning, rate limits, and schema discovery in one call.

## Known failure modes

- Target URL is unreachable or returns a network error — investigation cannot proceed
- Target endpoint returns an HTML page (e.g. landing page) rather than an API response — limited useful metadata extractable
- Rate limits or IP blocks on the target API prevent probing — partial results only
- Target API requires mandatory auth before returning any response — auth scheme may be inferred but response structure unavailable
- Malformed or non-standard OpenAPI specs may not be detected
- Non-JSON response bodies limit response structure analysis

## How this service works

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.

## Output

A structured report covering the detected authentication scheme (e.g. Bearer, API key, Basic), content type, API version, rate limit headers, any discovered OpenAPI/Swagger spec URL, and an annotated sample of the JSON response structure returned by the endpoint.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "endpoint": {
   "type": "string",
   "description": "API URL to investigate (e.g. https://api.example.com/v1/users)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "args": {
   "endpoint": "https://agent402.tools/api/pricing"
  },
  "pack": "api-investigation",
  "steps": [
   {
    "ok": true,
    "slug": "url-parse",
    "result": {}
   },
   {
    "ok": true,
    "slug": "http-check",
    "result": {}
   },
   {
    "ok": true,
    "slug": "http-headers",
    "result": {}
   },
   {
    "ok": true,
    "slug": "extract",
    "result": {}
   },
   {
    "ok": true,
    "slug": "html-links",
    "result": {}
   },
   {
    "ok": true,
    "slug": "json-format",
    "result": {}
   },
   {
    "ok": true,
    "slug": "json-query",
    "result": {}
   }
  ],
  "summary": "7/7 steps succeeded"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent402-tools-api-investigation-8af363c1/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)