Execute a read-only SQL query (SELECT, SHOW, DESCRIBE, EXPLAIN). LIMIT is auto-appended to SELECT/WITH queries without one (default: server maxRows). Prefer specific columns over SELECT * to reduce response size. For data modification, use the "execute" tool instead.

Execute a data modification SQL statement (INSERT, UPDATE, DELETE, CREATE, ALTER, DROP, etc.). Set dryRun=true to validate without executing — uses EXPLAIN for DML, or previews the SQL for DDL. Always confirm destructive operations (DROP, TRUNCATE, DELETE without WHERE) with the user before executing. Not available in read-only mode.

List all databases on the MySQL server. Use this as a starting point to discover available databases before querying. Returns a JSON array of database names.

List all tables in the specified database (or the current database if not specified). Includes table comments when available. Use this before describe_table to find the exact table name.

Show the schema/structure of a table, including column names, types, constraints, and comments. Use this before writing queries to ensure correct column names and types. For inspecting all tables at once, use describe_all_tables instead.

Show the schema of all tables at once. Much more efficient than calling describe_table for each table individually. Warning: response can be large for databases with many tables — prefer describe_table for specific tables when possible.

Safely add a comment to a table or column. This tool only modifies comments — it cannot alter table structure, column types, or data. Set dryRun=true to preview the generated SQL without executing it. Use describe_table first to verify column names. Not available in read-only mode.