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CheckDigit

by checkdigit.mike-tusa.workers.dev · remote · no sign-in to list tools · v0.2.1 · published by dev.workers.mike-tusa.checkdigit

Offline check-digit validation for IBAN, BIC, EU VAT, GTIN/EAN/UPC and ISBN. Format check only.

Changes · 1
CompareRegistry entry

2 tools: 1 change things and 1 only read.

Scanned Oct 21, 2026

1 check matched something in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http checkdigit https://checkdigit.mike-tusa.workers.dev/mcp

Findings

Matches of fixed checks, with the text they matched.

1 warn
  • Warnvalidate_code

    The server marks "validate_code" read-only (readOnlyHint: true), and its own name, description or input give the class "write".

    Matched text

    annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "validate_code" says "validate": a word for reading.

    What this check looks for

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

2 tools

Changes things 1Claude Code: ask
  • validate_codeCheck the format and check digits of one identifier: IBAN (ISO 13616, per-country length and layout), BIC/SWIFT (ISO 9362 format and country), EU VAT number (offline checksum, VIES…1 finding

    Why it is in this group

    • The name "validate_code" says "validate": a word for reading.
    • The input takes a statement or command to run (input.code), which can change anything it can reach.
    • The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.

    Findings

    • Warn

      The server marks "validate_code" read-only (readOnlyHint: true), and its own name, description or input give the class "write".

      Matched text

      annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "validate_code" says "validate": a word for reading.

      What this check looks for
    Description, as the server wrote it
    Check the format and check digits of one identifier: IBAN (ISO 13616, per-country length and layout), BIC/SWIFT (ISO 9362 format and country), EU VAT number (offline checksum, VIES not queried), GTIN/EAN-8/UPC-A/EAN-13/GTIN-14 (GS1 mod 10) or ISBN-10/13. type "auto" (default) detects the type from the shape. Returns valid, a reason when invalid (e.g. the expected check digit), and normalized/formatted forms. Format check, not a compliance check: valid does not mean the account, registration or product exists. The code is sent in a POST body and not stored or logged. Read-only. Same engine, keys and limits as POST /v1/{type}.

    Annotations the server declares

    • title: Validate code
    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false
Only reads 1Claude Code: allow
  • get_metaReturn the service version and build, supported IBAN and VAT countries, GTIN formats, the disclaimer and the current limits.No findings

    Why it is in this group

    • The name "get_meta" says "get": a word for reading.
    Description, as the server wrote it
    Return the service version and build, supported IBAN and VAT countries, GTIN formats, the disclaimer and the current limits. Does not count as a check. Read-only. Same data as GET /v1/meta.

    Annotations the server declares

    • title: Service info
    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 0.2.1. Values in angle brackets are yours to fill in.

claude mcp add --transport http checkdigit https://checkdigit.mike-tusa.workers.dev/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json
{
  "permissions": {
    "allow": [
      "mcp__checkdigit__get_meta"
    ],
    "ask": [
      "mcp__checkdigit__validate_code"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as checkdigit. Review it before you use it.