Register a MySQL-compatible database connection at runtime.

Tests the connection with SELECT 1 before caching. If a connection with the same name already exists, it is closed and replaced.

Args: name: A human-readable identifier for this instance (used as instance_id). host: Database host or IP address. port: Database port (e.g. 3306). user: Database username. password: Database password. database: Optional default database/schema. charset: Connection charset, defaults to utf8mb4.

Returns: JSON string with instance_id and status, or error details.

List all registered database instances.

Returns: JSON array of instances. Passwords are never included.

Execute a SQL statement on a registered instance.

SQL is classified before execution:

• Read-only (SELECT/SHOW/WITH/EXPLAIN/DESC): executes directly.

• Destructive (DROP/DELETE/UPDATE/INSERT/ALTER/TRUNCATE/CREATE/...): requires confirm_destructive=true.

• Blocked (OUTFILE/DUMPFILE/LOAD_FILE/SHUTDOWN/KILL): always rejected.

Args: instance_id: The instance name from register_instance. sql: The SQL statement to execute. database: Optional database to switch to before executing. confirm_destructive: Set to true to allow destructive operations.

Returns: JSON string with query results (columns/rows/row_count) or affected_rows for DML, or error/safety rejection details.

List all databases on a registered instance.

Args: instance_id: The instance name from register_instance.

Returns: JSON array of database names, or error details.

List tables in a database with row count and size.

Args: instance_id: The instance name from register_instance. database: The database name to list tables from.

Returns: JSON array of {table, rows, size_mb, engine, comment}, or error.

Get column info and CREATE TABLE DDL for a specific table.

Args: instance_id: The instance name from register_instance. database: The database name. table_name: The table name.

Returns: JSON with {columns: [...], ddl: "..."}, or error details.