List all tables available in the database, with a short description and the number of rows of each table. Use this first when you do not know the schema, before writing any SQL. No SQL is required.

Describe the structure of one table: columns with name, type, nullable and primary_key flags, plus foreign-key relationships such as 'orders.customer_id -> customers.id'. Use this after list_tables to understand the schema before writing SQL. Pass a table name that was returned by list_tables; unknown names produce a clear error.

Execute a single read-only SQL statement (SELECT or WITH ... SELECT) against the shop database. JOIN, LEFT JOIN, GROUP BY, HAVING, ORDER BY, LIMIT/OFFSET, DISTINCT, CASE and CTE are supported. If you do not know the schema yet, call list_tables and describe_table first. Rules enforced by the server: exactly one statement per call (multi-statement SQL is rejected), and no data or schema modification (INSERT, UPDATE, DELETE, CREATE, DROP, ALTER, ATTACH, DETACH, VACUUM, REINDEX, PRAGMA are rejected). The database is opened read-only, so writes are impossible. The result is structured: {columns, rows, row_count, truncated, execution_time_ms}. If truncated is true, only the first row_count rows were returned due to the server-side limit (max_rows, default 1000): refine the query, e.g. add LIMIT, WHERE or aggregation, instead of assuming the data is complete.