# AgentShelf ISBN-13 Regex Extractor

> AgentShelf ISBN-13 Regex Extractor is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.008/call, status unknown (last checked 2026-09-29).

Extracts up to 20 ISBN-13 digit strings from a given text block using regex matching, returning all matches found.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/regex-isbn?utm_source=zero.xyz
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentshelf-isbn-13-regex-extractor-ad54a6cb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZY-Dyir7sVRmSiLR9GFXP

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 agentshelf-isbn-13-regex-extractor-ad54a6cb -d '<json body>'
```

Example prompt: Can you extract all ISBN-13 numbers from this text? 'The following titles are available: 978-3-16-148410-0 and 9780306406157, along with several others listed below...'

## When to prefer this

Use this endpoint when you need fast, deterministic ISBN-13 extraction from text without any network dependency or LLM involvement. Prefer the free sandbox endpoint POST /v1/sandbox/regex-isbn for testing before paying. Choose this over manual parsing or LLM-based extraction when you need consistent regex-based results at low latency and exact cost ($0.008 USDC). Suitable for batch document processing pipelines where ISBN harvesting is a recurring step.

## Known failure modes

- Empty match list returned if no ISBN-13 patterns found in text — still billed at $0.008 USDC
- Text exceeding 100,000 characters will be rejected (input validation error)
- Empty or missing 'text' field causes request failure
- More than 20 matches are capped silently at 20 results
- Malformed ISBN-like strings (e.g. 12-digit or non-ISBN-13 patterns) may not be extracted

## How this service works

Call when an agent needs ISBN-13 digit strings extracted from text, capped at 20 matches. An empty match list is billed. No network. Exact $0.008 USDC. Prefer unpaid POST /v1/sandbox/regex-isbn first.

## Output

A list of up to 20 ISBN-13 digit strings found in the input text, returned as regex matches. An empty list is returned (and still billed) if no ISBNs are found. Results are pure digit strings (13 digits each), extracted without network calls or LLM inference.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "text": {
   "type": "string",
   "examples": [
    "9780306406157"
   ],
   "maxLength": 100000,
   "minLength": 1,
   "description": "Input for this SKU. The route description says whether it is plain text, a URL, base64 bytes, or an already-encoded token."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentshelf-isbn-13-regex-extractor-ad54a6cb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)