Ask a general-purpose AI assistant when a UK company's Corporation Tax is due and you'll usually get a confident answer. Sometimes it's right. Tax dates and rates are rule-based, though, so they're a good fit for a deterministic tool the model can call instead of guessing. This post shows how to connect an assistant to a free, public Model Context Protocol (MCP) server that does exactly that for UK limited companies, and what you get back when you call it directly with curl. What ...