Jp Corporate Id MCP server

mcp-jp-corporate-id

日本語版はこちら

An MCP (Model Context Protocol) server that validates and normalizes Japanese corporate numbers (houjin bangou) and qualified invoice issuer registration numbers, and normalizes/matches company names across common notation variants.

No network access is used at all (v1 calls no external APIs). Every check is done with formulas and dictionary data embedded in the code.

Read this first

or that an invoice registration is currently valid.** For real-world verification, always check the official National Tax Agency sites directly:

• This tool only validates the format* of numbers and names. It does NOT verify that a company actually exists,

individual My Number (12 digits) have the same length, and this tool cannot distinguish which kind of number it was given. calculatecheckdigit always includes a caution about this in its response.

• Corporate Number Publication Site
• Qualified Invoice Issuer Publication Site
• Never enter a Japanese Individual Number (My Number). A company registration number (12 digits) and an

submitted.

• This server never logs request input, and validation-error messages never echo back the raw number that was

Tools (7 total)

Every tool's response includes the primary sources (sources) behind its logic.

1. validatecorporatenumber

Verifies whether the check digit of a 13-digit corporate number is correct. Accepts full-width digits, hyphens, and whitespace, which are normalized before validation. If the normalized length isn't 13 digits, or the check digit doesn't match, the tool returns valid: false rather than throwing.

2. calculatecheckdigit

Computes the check digit from a 12-digit company registration number (assigned based on commercial registry records) and derives the 13-digit corporate number. Throws if the normalized input isn't exactly 12 digits (no guessing or zero-padding).

Caution: a 12-digit number could just as easily be a My Number (individual number) as a company registration number. Every response includes a caution field reminding callers never to submit a My Number. If the registry office code portion falls outside the typical range (0100–5000) confirmed from primary sources, a note is added.

3. validateinvoicenumber

Validates a qualified invoice registration number ("T" + 13 digits).

Shortened. The full README is on GitHub.