MCP server that catches mistyped barcodes, ISBNs, VINs and other public structured identifiers before a bad one causes a rejected listing, a bounced claim or a corrupted record.

@toolstop/check-digits

toolstop

check-digits

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		@@ -71,3 +71,3 @@ // The single source of truth for this server. Both transports (Worker HTTP and
		name: "check-digits",
		version: "0.2.1",
		version: "0.2.2",
		instructions:
		@@ -74,0 +74,0 @@ "Catches mistyped barcodes, VINs, ISBNs and other public structured " +

		{
		"name": "@toolstop/check-digits",
		"version": "0.2.1",
		"version": "0.2.2",
		"mcpName": "dev.toolstop/check-digits",
		@@ -5,0 +5,0 @@ "description": "MCP server that catches mistyped barcodes, ISBNs, VINs and other public structured identifiers before a bad one causes a rejected listing, a bounced claim or a corrupted record.",

		@@ -71,4 +71,30 @@ # mcp-check-digits

		Running over stdio, nothing leaves your machine at all.
		What is recorded. Saying only what is not stored would be a half-answer, so
		here is the whole row. One record per request, retained 90 days:

		\| \| \|
		\|---\|---\|
		\| The call \| Server name and version, MCP method, tool name, outcome, error class (never the message), duration, result size \|
		\| The client \| Client name and version and protocol version as your software reports them, plus a truncated user agent \|
		\| Coarse location \| Country and Cloudflare data centre. Never a precise location \|
		\| Argument shape \| Field names with types and lengths, for example `str:22`. Never a value \|
		\| A session id \| See below \|

		The session id is derived from your network, not from you. It is a hash of
		your user agent, the date, this server's name, and the network block your
		request came from, truncated to a /24 (IPv4) or /48 (IPv6) before anything
		hashes it. It exists to count distinct sessions in a day and it deliberately
		cannot do more: it does not link across days, and two people behind the same
		network running the same client are indistinguishable in it.

		That truncation was added on 2026-08-10 and it fixed a real weakness rather than
		adding a nicety. The id previously covered the full client address, and an
		8-byte hash does not conceal a 32-bit value when the other inputs are public, so
		it could be walked back to a single address. It no longer can. Being specific
		about this matters more than looking clean: an unknown vendor asking you to
		route data through their server owes you the actual answer.

		Running over stdio, none of this happens. The server runs on your machine and
		deliberately does not phone home, so there is no row and no network request.

		## What it does not do
		@@ -75,0 +101,0 @@

@toolstop/check-digits - npm Package Compare versions

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