A McDonald's coupon optimizer that refuses to guess prices

What it does

Built on McDonald’s China’s official MCP server, this Python skill answers two questions: “what’s the cheapest way to order this meal right now” and “how much money am I throwing away.” It pulls the live menu and prices for your current store, enumerates combos of items, meals, coupons, and add-ons, then prices every candidate through the MCP calculate-price endpoint — real pricing, not model guesswork. The long-term side audits your coupon inventory and order history, flagging coupons about to expire as literal money evaporating.

The interesting bit

The core discipline is refusing to estimate. When a coupon’s value can’t be derived from the menu (like one whose title contains no number and matches no product), it’s priced by feeding the coupon’s product code into calculate-price and measuring — or honestly reported as “value unknown.” The demo even keeps coupons that look unresolvable because the menu snapshot was taken at 21:59 and breakfast items weren’t listed, rather than faking a match. It also distinguishes “coupons usable at this store” from “coupons in your wallet” — the demo shows 2 vs 9, meaning a naive tool would miss 7 expiring breakfast coupons entirely.

Key highlights

• Zero third-party dependencies (stdlib only); the offline demo replays recorded MCP responses and doubles as an end-to-end regression test
• Detects and warns against coupon-driven add-on traps — using a coupon often costs more than skipping it
• Schedules coupon usage against your actual ordering frequency: if you’ll only place one order before they expire, it tells you which ¥6.6 of value is mathematically doomed
• Points audit found 15 of 24 redemption items past their deadline while the API still marks them “on sale”
• Reminds you about unclaimed coupons — the only zero-cost savings source

Caveats

• Tied to McDonald’s China’s MCP (mcp.mcd.cn); useless outside that ecosystem
• Refund handling is shaky by data limitation: the order API doesn’t return refund amounts, so totals may run slightly high — the README admits this rather than hiding it
• Some coupon values genuinely can’t be computed and are reported as unknown, which is honest but means the audit is sometimes incomplete

Verdict

A surprisingly rigorous piece of glue code around one company’s MCP server — worth a look if you order McDonald’s in China or want a template for “LLM skill that never hallucinates prices.” If you were hoping for a general-purpose coupon engine, this isn’t it."