Mapbox Location Grounding

This teaches Claude to stop hallucinating location data by grounding answers in live Mapbox APIs. Instead of guessing at restaurant names or travel times from training data, it composes reverse geocoding, POI search, place details, and isochrones into cited responses with ratings, prices, and reachability polygons. The single ground_location_tool call handles most cases, but you can manually chain tools if needed. Especially useful for "what's near me" questions, travel time comparisons, and anything where stale POI data or made-up business hours would wreck the user experience. It pushes hard on always retrieving live data rather than answering from memory, which is the right default for location queries.