List every available health table and return the curated semantic layer: what each metric measures, which aggregate function is valid for it, and the known traps in the data. Call this before writing any query.

Run a read-only DuckDB SQL query against the health tables. Call health_schema first so you know the columns and the correct aggregate function for each metric.

Generate a summary across heart rate, sleep, activity, blood oxygen, workouts and CPAP therapy for a period. The window is either a named relative period or explicit dates; the reply states which window was used and why, so check period.start and period.end against what you asked for. Use health_query for anything more specific.