# AgentShelf ISBN-10 Checksum Validator

> AgentShelf ISBN-10 Checksum Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-02).

Validates whether a given ISBN-10 string has a correct checksum digit

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-isbn-10?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentshelf-isbn-10-checksum-validator-f119aa00
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3bmmXAIt1zKsgt7ElP2-r

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-10-checksum-validator-f119aa00 -d '<json body>'
```

Example prompt: Can you check if the ISBN-10 '0306406152' has a valid checksum?

## When to prefer this

Use this endpoint when you need a deterministic, no-LLM, no-network ISBN-10 checksum validation without building the Modulus 11 algorithm yourself. Prefer the free sandbox endpoint POST /v1/sandbox/check-isbn-10 for testing; use this paid endpoint in production workflows where reliability and a verified response matter. Not suitable for ISBN-13 validation.

## Known failure modes

- Input string is empty or missing — returns error due to minLength constraint
- Input longer than 20000 characters — rejected by maxLength
- Malformed JSON body — HTTP 400 or parse error
- Payment of $0.004 USDC not provided — HTTP 402 Payment Required
- Input is an ISBN-13 rather than ISBN-10 — may return invalid or misapplied result

## How this service works

Call when an agent needs whether an ISBN-10 checksum is valid. Exact $0.004 USDC. Prefer unpaid POST /v1/sandbox/check-isbn-10 first.

## Output

Returns a boolean or status indicating whether the provided ISBN-10 string passes the standard Modulus 11 checksum algorithm, confirming if the identifier is structurally valid.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "description": "JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN."
  },
  "value": {
   "type": "string",
   "examples": [
    "0306406152"
   ],
   "maxLength": 20000,
   "minLength": 1,
   "description": "Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar."
  },
  "schema": {
   "description": "JSON Schema document for schema-check SKUs. Omit it on string checks."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentshelf-isbn-10-checksum-validator-f119aa00/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)