# Touchstone x402 Door Verifier

> Touchstone x402 Door Verifier is a paid API for AI agents from touchstone.locomot.io, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).

Checks a given x402-protected URL against the catalogue index to verify whether the payTo address and price match what the catalogue claims, flagging mismatches, dead hosts, and self-contradicting entries.

## Facts

- Endpoint: GET https://touchstone.locomot.io/door
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/touchstone-x402-door-verifier-19c5c99e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-2qyb0DWDac-WNDwByzmF

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 touchstone-x402-door-verifier-19c5c99e
```

Example prompt: Before I pay this x402 endpoint at https://api.example.com/data, check it against the catalogue — does the payTo address and price actually match what the index claims?

## When to prefer this

Use this endpoint any time an AI agent or automated system is about to make an x402 micropayment and needs to confirm the payment target is legitimate. It is specifically valuable when the payTo address or price differs from what the catalogue advertises — a known issue affecting 28.6% of listings. Prefer this over manual inspection or trusting the live 402 response alone, especially for hosts not previously paid.

## Known failure modes

- URL not found in x402 index — verdict returns 'unknown'
- Host is dead or unreachable — flagged in flags array
- Self-contradicting host where catalogue entry is internally inconsistent
- Input URL is not an x402 resource — may return unknown or error
- Network timeout reaching the live host during probe comparison

## How this service works

Before you pay an x402 door, check it against its catalogue entry. A nightly probe of EVERY host in the x402 index (1,618 hosts, 15,227 listings, 100% coverage): the live 402's real payTo and price versus what the catalogue claims, plus dead and self-contradicting hosts. 28.6% of listings sit on a host the catalogue gets wrong — one names one payee and pays another across 965 listings. Same computation as GET; send the parameters as a JSON body. Free sample, no payment required: GET /play/door

## Output

Returns a verdict string (catalogue_matches | catalogue_disagrees | unknown), arrays of payTo mismatches and price mismatches with details, a list of flags, an optional caveat string, the number of doors opened in the probe, and the count of listings in the index.

## 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",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "description": "the x402 resource URL you are about to pay"
      },
      "full": {
       "type": "boolean",
       "description": "include every sampled observation"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "verdict"
   ],
   "properties": {
    "flags": {
     "type": "array",
     "items": {
      "type": "string"
     }
    },
    "caveat": {
     "type": "string"
    },
    "verdict": {
     "type": "string",
     "description": "catalogue_matches | catalogue_disagrees | unknown"
    },
    "doors_opened": {
     "type": "integer"
    },
    "payto_mismatch": {
     "type": "array",
     "items": {
      "type": "object"
     }
    },
    "price_mismatch": {
     "type": "array",
     "items": {
      "type": "object"
     }
    },
    "listings_in_index": {
     "type": "integer"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/touchstone-x402-door-verifier-19c5c99e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from touchstone.locomot.io](https://www.zero.xyz/host/touchstone.locomot.io/llms.txt)