Returns top 8-10 digit HTS code candidates (with MFN/FTA rates and CBP CROSS ruling links) for a product description. Results are CANDIDATES for pre-broker screening, not a classification ruling. IMPORTANT: the HTS uses legal terminology, not trade names — BEFORE CALLING, rewrite the product description into HTS-style material + use nouns (e.g. 'pink kids backpack' → 'travel bags of man-made fibers'; 'water bottle' → 'vacuum flask' or 'bottle of plastics'). If you get 0 results, retry with 2-3 different phrasings.

Returns the HTS code's MFN/FTA base rate, ALL active chapter 99 rules (IEEPA/301/232 additional duties) matching the origin as verbatim text, and MPF/HMF fees. The LLM should walk the chapter-99 exception chains itself to stack the right duty layers, explain each step to the user, and always note this is an estimate.

Saves HTS codes (with optional origin) to a local watchlist. After each dataset refresh, call check_tariff_updates to see whether the rates on these codes changed. This is how you track 2025-2026 tariff volatility without manual re-checking.

Compares the current HTS snapshot with the previously fetched one. Call without codes to check the whole watchlist. Returns each change: code, column (general/special/other/additionalDuties), old → new value.

Fetch date, source, license, row counts — use to check data freshness.