# International Address Formats – PO Box Heuristic Check

> International Address Formats – PO Box Heuristic Check is a paid API for AI agents from address-formats.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-11-02).

Heuristically detects whether an address line contains PO box wording across multiple languages including English, German, French, and Spanish.

## Facts

- Endpoint: GET https://address-formats.x402tookit.com/po-box-check?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/international-address-formats-po-box-heuristic-check-3cc191bb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_egzHlb_pKTKYPbf1UXAwL

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 international-address-formats-po-box-heuristic-check-3cc191bb
```

Example prompt: Can you check if this address line looks like a PO box — 'Postfach 4521, 80331 München' — and tell me what language the pattern matched in?

## When to prefer this

Use this endpoint when you need a fast, lightweight heuristic signal about whether an address line is a PO box across multiple languages — particularly when input addresses may be in English, German, French, Spanish, or other European languages. Prefer this over a full address validation service when the only question is PO box vs. physical address, and when a heuristic (non-authoritative) check is sufficient. Not suitable when you need guaranteed accuracy or official postal verification.

## Known failure modes

- Missing required 'text' query parameter returns an error
- Ambiguous or abbreviated address text may produce false negatives (heuristic, not proof)
- Very short or single-character input may yield no pattern matches
- Language not in the supported set may return no match even for genuine PO boxes
- Degraded flag may be set if internal pattern data was partially unavailable

## How this service works

Heuristic check whether an address line uses PO box wording in English, German, French, Spanish and more; not proof.

## Output

Returns a verdict (e.g. 'is PO box' or 'not detected'), matched patterns with their language labels and weak/strong flags, a human-readable summary, a disclaimer about heuristic accuracy, the list of languages covered by the check, and any reasons or caveats. May include a degraded flag if some checks could not be performed.

## 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"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "text"
     ],
     "properties": {
      "text": {
       "type": "string",
       "description": "An address line, e.g. 'P.O. Box 123'"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "input": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "matches": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "object",
        "properties": {
         "weak": {
          "type": [
           "boolean",
           "null"
          ]
         },
         "pattern": {
          "type": [
           "null",
           "string"
          ]
         },
         "language": {
          "type": [
           "null",
           "string"
          ]
         },
         "matchedText": {
          "type": [
           "null",
           "string"
          ]
         }
        }
       }
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "dataSnapshot": {
       "type": [
        "null",
        "string"
       ]
      },
      "languagesCovered": {
       "type": [
        "array",
        "null"
       ],
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/international-address-formats-po-box-heuristic-check-3cc191bb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from address-formats.x402tookit.com](https://www.zero.xyz/host/address-formats.x402tookit.com/llms.txt)