ISBN Validator Skill

Overview

ISBN Validator works by analyzing ISBN-10 and ISBN-13 numbers, validating their checksum algorithms, and extracting information about the group, publisher, and title identifiers. Handles both formats with or without separators.

Live Test ISBN Validator Skill Skill →

The tool

Once your client is connected to the VerveKit server, this appears in its tool list as ISBNValidatorSkill. It is read-only and open-world — it fetches and never mutates anything on your side — so most clients call it without asking you to confirm.

Tool call

{
  "name": "ISBNValidatorSkill",
  "arguments": {
    "isbn": "978-0-306-40615-7"
  }
}

You do not name the tool yourself; the model picks it. Asking about 978-0-306-40615-7 in the terms this skill covers is enough for it to reach for ISBNValidatorSkill on its own — naming it explicitly also works, and is the way to force the call.

Connecting

One server URL covers every skill in the catalog, including this one. Authorization is OAuth: the client opens a browser once, and there is no key to paste into a config file.

{
  "mcpServers": {
    "vervekit": {
      "url": "https://api.vervekit.com/v1/mcp"
    }
  }
}

Per-client setup — Claude, Cursor, VS Code, ChatGPT — is on the MCP setup page.

Arguments

These are the properties on the tool's inputSchema, so a well-behaved client validates them before the call is made. Premium arguments are accepted on every plan but only take effect on plans that include them.

Argument	Type	Description
`isbn`Required	string	The ISBN number to validate (ISBN-10 or ISBN-13, with or without separators)

What the model gets back

The result carries a structuredContent object matching the tool's declared outputSchema, so a client reads fields without parsing prose. status is "ok" and error is null on success; a null field means the value was not available for that input, not that the call failed.

Result

{
  "status": "ok",
  "error": null,
  "data": {
    "valid": true,
    "isbn": "978-0-306-40615-7",
    "type": "ISBN-13",
    "normalized": "9780306406157",
    "formatted": "978-0-306-40615-7",
    "checksum_valid": true,
    "prefix": "978",
    "group": "0",
    "publisher": "306",
    "title": "40615",
    "check_digit": "7",
    "error": null
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Field	Type	Example	Description
`valid`	boolean	`true`	Whether the ISBN is valid
`isbn`	string	`978-0-306-40615-7`	Normalized ISBN number
`type`	string	`ISBN-13`	ISBN format (ISBN-10 or ISBN-13)
`normalized`	string	`9780306406157`	The ISBN with hyphens and spaces removed
`formatted`Premium	string	`978-0-306-40615-7`	ISBN with proper hyphenation
`checksum_valid`	boolean	`true`	Whether the check digit matches the rest of the number
`prefix`	string	`978`	GS1 prefix, 978 or 979 for a 13-digit ISBN
`group`	string	`0`	Registration group, identifying the country or language area
`publisher`	string	`306`	Publisher element of the ISBN
`title`	string	`40615`	Title element, identifying the edition within the publisher
`check_digit`Premium	string	`7`	Check digit value
`error`	object	`null`	Why the ISBN was rejected; null when it is valid

Failure modes

Errors come back as tool errors carrying a sentence the model can act on, not a bare status code. Error handling covers the full list.

Status	What it means
`400` / `422`	The arguments did not validate. The message names the offending one.
`401`	The OAuth session is invalid or expired — reconnect the server.
`403`	Blocked by a key restriction or an IP allow-list. Never a bad identity.
`404`	This skill is not part of VerveKit. Check the catalog.
`429`	Out of credits, or a brief rate limit. The message tells them apart.

A call costs 2 credits each time the tool actually runs; a model that reasons about the tool without calling it costs nothing.

Use cases

Book Cataloging: Validate ISBNs when adding books to library catalogs or inventory management systems
E-commerce: Verify ISBN accuracy in book listings on e-commerce platforms to prevent listing errors
Publishing: Validate ISBNs during book registration and publishing workflows to ensure correct formatting
Data Quality: Check ISBN validity in book databases during data cleaning and migration projects

Other ways to use ISBN Validator Skill

Set up ISBN Validator Skill on VerveKit, or reach the same source a different way. Your VerveKit account and credits work on all of them — one key, one balance.

Call it as a REST APIOne HTTPS endpoint and an x-api-key header, with SDKs for Node, Python and .NET.APIVerve →Reference →

Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.VerveSheets →Reference →