io.github.qinisolabs/localecheck (MCP Server)

The io.github.qinisolabs/localecheck MCP server provides verified locale data for AI agents, focused on everyday non-US inputs. It covers UK and US formats and supplies correct values for dates, phone, currency, tax, holidays, and addresses, helping agents avoid incorrect assumptions and impossible inputs.

🛠️ Key Features

Verified locale-correctness tools for AI agents
Correct handling for: dates, phone, currency, tax, holidays, and addresses
Coverage: UK + USA (v1), expanding

🚀 Use Cases

Parse and interpret date formats such as 03/04
Apply locale-specific tax rules (including historical invoices)
Format currency amounts (e.g., €1,234.50)
Determine bank holidays for delivery date calculations
Validate address formats for UK/US

⚡ Developer Benefits

Flags impossible inputs instead of guessing
Uses verified answers to improve agent reliability
Free access with no API key

⚠️ Limitations

Coverage is UK and USA only in v1; expansion is not specified beyond that

localecheck

Locale-correctness tools for AI agents. Agents are systematically wrong about everyday non-US data — they read 03/04 as March 4 in the UK, apply today's VAT rate to a historical invoice, format €1,234.50 for a German reader, and miss bank holidays in delivery dates. localecheck gives them verified answers and flags impossible inputs instead of guessing.

Coverage: UK + USA (v1), expanding. Free, no API key.

Packages

Package

Install

Use

TypeScript (primary)

packages/localecheck-ts

npx -y localecheck (live on npm)

MCP server and importable library

Python

packages/localecheck-python

from source (PyPI release coming soon)

MCP server, importable library, REST API

Both wrap the same authoritative libraries (libphonenumber, CLDR/Intl, date-holidays) and share the same hand-curated tax data.

Repo map

packages/localecheck-ts — primary TypeScript package (MCP + library)

packages/localecheck-python — Python package + FastAPI REST API

eval/ — benchmark harness: how often raw LLMs get this wrong

benchmark.html — shareable results page · BUSINESS_MODEL.md — strategy · PUBLISH.md — release steps · LOCAL_TEST.md — test before publishing

Status & caveats

UK VAT history is reliable for the modern era (standard rate). US state sales-tax values are 2025 state base rates (local taxes add on top) — verify against an authoritative feed before live invoicing. Addresses parse + extract a valid postcode/ZIP but don't verify deliverability.

Code: Apache-2.0. Curated tax data: see BUSINESS_MODEL.md.

io.github.qinisolabs/localecheck