# x402-tools Signature Classifier (sigclass)

> x402-tools Signature Classifier (sigclass) is a paid API for AI agents from openclawproductions.com, paid per call via x402, $0.03/call, status unknown (last checked 2026-10-11).

Classifies EIP-3009 signature failure reasons from facilitator error messages returned in HTTP 402 responses

## Facts

- Endpoint: GET https://openclawproductions.com/api/v1/sigclass?utm_source=zero.xyz
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-tools-signature-classifier-sigclass-41ab50b0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_z_XqaaCE7GKtYnCMiv5Ox

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 x402-tools-signature-classifier-sigclass-41ab50b0
```

Example prompt: Classify this EIP-3009 revert string I got back from the OpenX402 facilitator in a 402 response: 'TransferWithAuthorization: invalid nonce' — what does it mean and which sigclass category does it fall into?

## When to prefer this

Use this endpoint when you need to programmatically classify or diagnose EIP-3009 signature failure reasons returned by the OpenX402 facilitator in HTTP 402 responses. It is purpose-built for x402 protocol debugging and is the only known paid diagnostic SKU specifically for sigclass categorization. Prefer it over generic error-parsing logic when dealing with facilitator invalidReason, errorReason, or invalidMessage fields in x402 flows.

## Known failure modes

- Unpaid or unauthenticated requests return HTTP 402 with eip3009 extras (payment required before classification is returned)
- Missing required 'input' object or 'type'/'method' fields returns a validation error
- Unsupported HTTP method (only GET, HEAD, DELETE allowed) returns an error
- Empty or missing 'reason' query parameter may return a generic or null classification
- OpenX402 facilitator unavailability may cause payment settlement failures

## How this service works

Paid x402 diagnostics. Unpaid paid-SKU requests return HTTP 402 with eip3009 extras. Facilitator: OpenX402 only.

## Output

Returns a JSON object containing the SKU name ('sigclass'), a classification or diagnostic note about the provided EIP-3009 revert/error string, the price ($0.03), and a title. The classification tells the caller what category of signature or authorization failure the facilitator reason corresponds to.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "reason": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  },
  "inputSchema": {
   "type": "object",
   "required": [
    "type",
    "properties"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "object"
    },
    "required": {
     "type": "array",
     "items": {
      "type": "string"
     }
    },
    "properties": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "sku": "sigclass",
  "note": "Example paid JSON shape. Not a live settle.",
  "price": "$0.03",
  "title": "Sig Class"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-tools-signature-classifier-sigclass-41ab50b0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from openclawproductions.com](https://www.zero.xyz/host/openclawproductions.com/llms.txt)