Read this first, once per session: the Rowbase knowledge base — recommended workflow, safety rules (read-only model, one statement per call), the TOON output format and SQL dialect notes. Use it before any other tool; it needs no connection. Returns a markdown document.

List the user's saved database connections exposed to MCP. Call this first to get the exact connection names every other tool requires. Returns a table connections[N]{name,driver,env,mode,database,tunnel} — mode is the EFFECTIVE read-only/read-write mode for MCP; env 'prod' means be extra careful — plus writes_enabled_in_mcp. No pagination: all exposed connections are returned.

List the databases on a connection's server and which one is current. Use it when a connection has no database selected, or to work in another database (pass database to later calls); to list tables inside a database use tables instead. Returns current, databases[N] (user databases first) and system[N]. SQLite returns an empty list (one file = one database). On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).

List all tables and views of a connection/database with approximate row counts — the entry point for browsing. Use search_schema instead when you look for a concept (e.g. 'invoice') across table AND column names, and describe once you know the table. Returns tables[N]{name,kind,approx_rows} (kind = table|view; approx_rows is an estimate, may be null; use count for exact numbers). Returns every match, no pagination. On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).

Show the structure of one known table: columns with type, nullability, key, default, foreign-key target (fk = table.column — use it to write JOINs) and comment, plus indexes and the tables that reference it. Use it before writing SQL against a table; use search_schema if you don't know the table name yet. Returns table, sql_name (properly quoted name for SQL), columns[N]{name,type,nullable,key,default,fk,comment}, indexes[N]{name,unique,columns} and referenced_by[N]{table,column,ref_column}. On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).

Find tables and columns whose name contains a keyword (case-insensitive substring; on MySQL also column comments). Use it when you know WHAT you are looking for but not WHERE it is stored; use tables instead to browse everything and describe for one known table. Returns matches[N]{table,column,type}, one row per matching column (a table-name match lists all its columns), capped at 500 rows (truncated: true when cut). On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).

Peek at a few real rows of one table (SELECT * … LIMIT n, in storage order, no sorting) to see what the data looks like before writing a query. Use query instead for specific columns, joins, sorting or aggregates, and count when you only need a number. Returns rows[N]{all columns} plus rows, truncated (true = more rows exist) and ms. Default 20 rows, capped by the server's max rows setting. On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).

Return the exact number of rows in a table, optionally filtered — use it to size a result before fetching it or to answer 'how many' questions. Use query instead for grouped counts (GROUP BY) or counts over joins. Returns a single line: count: N. May be slow on very large unindexed filters (timeout from settings). On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).

Run exactly ONE SQL statement — the general tool for answering questions: specific columns, JOINs (follow fk from describe), filters, sorting, GROUP BY. Read-only connections accept only SELECT/SHOW/DESCRIBE/EXPLAIN/WITH/VALUES/TABLE (+PRAGMA on SQLite); multiple statements are refused. Prefer sample/count for simple peeks and totals, explain for performance. A LIMIT is added automatically when missing. Returns rows[N]{columns} plus rows, truncated (true = more rows exist — narrow with WHERE or raise limit) and ms; write statements (only if writes are enabled) return affected instead. On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).

Show how the database will execute a SELECT (its query plan) to diagnose slow queries or check index use — use it instead of query when the question is about performance, not data. With analyze=true the statement is actually executed to report real timings (can be slow on big tables). Returns the plan as rows plus a hint: MySQL type=ALL or PostgreSQL 'Seq Scan' means a full table scan (consider an index or a narrower WHERE). SQLite uses EXPLAIN QUERY PLAN. On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).

Find which table holds a UUID value as its primary key — for schemas that store references as UUIDs without foreign keys (1C-style Ref keys, columns like SenderAddress or Owner_Ref). Use it when describe shows no fk for a column whose values are UUIDs; use describe fk + query instead when real foreign keys exist. Searches tables whose single-column primary key can hold a UUID: the hint table first, then tables named like the column (SenderAddress → …Addresses), then all of them. Returns matches[N]{table,pk,label} (label = Description/Name/Number/Code of the row) and found_by, or searched_tables when nothing matched. On failure returns isError with 'error: ' (e.g. refused statement, unknown table, SQL error).