Check Digits

Overview

Check Digits is a Model Context Protocol (MCP) server: Catch a mistyped barcode, ISBN, VIN, NPI or LEI before a bad identifier corrupts a record. In practice that means any MCP-compatible AI assistant can call Check Digits's tools directly — the model decides when to use them in a conversation or agent run.

You can run Check Digits two ways: connect to the hosted endpoint at https://check-digits.toolstop.dev with no local install, or run it on your own machine via the npm package @toolstop/check-digits. The current release is v0.2.2, published under the MIT license, with source at toolstop/toolstop on GitHub.

Check Digits is listed under Development on mcp.site and works with any MCP client — Claude Desktop, Claude Code, Cursor, VS Code, Windsurf, Zed and the rest of the ecosystem — using the install snippets below. If you maintain Check Digits for toolstop.dev, claim this listing to verify ownership, earn the Verified badge, and keep the details current.

Installation

Settings → Connectors → Add custom connector
Name: Check Digits
URL:  https://check-digits.toolstop.dev