Execute a read-only SQL query against the MS SQL Server database. Accepts: a single SELECT / WITH...SELECT; a multi-statement batch led by DECLARE, INSERT, or CREATE TABLE # that writes ONLY to session-local #temp tables or @table variables (global ##temp is never allowed); or EXEC of a whitelisted stored procedure whose definition does not write to a persistent table. Writes to real tables, DDL on persistent objects, dynamic SQL, EXEC inside batches, and DBCC are blocked (server runs with MSSQL_READ_ONLY=true). Returns results as JSON or Markdown.

Get database schema information including tables, columns, data types, primary keys, and foreign keys. Optionally filter by table name.

List stored procedures in the database with their definitions and parameters. Optionally filter by procedure name.

Monitor database locks, blocking sessions, and potential deadlocks. Shows lock types, resources, and wait times.

Get database resource usage statistics including CPU, memory, active sessions, and top resource-consuming queries.

Test database connectivity and return server information: version, edition, current database, login, and server mode (read-only or write).

List all databases on the SQL Server instance with state, recovery model, compatibility level, and creation date.

List tables in the current database with schema, row count, and size in MB. Optionally filter by schema name.

Retrieve sample rows from a table (default 10, max 100). Safe way to preview data without writing SQL. Accepts 'table' or 'schema.table'.

Get foreign key relationships between tables: constraint name, from/to table and column, and delete/update actions. Optionally filter by table name (matches either side).

List views in the database with their full SQL definitions. Optionally filter by view name to get a single view's definition.

Search the SQL source code of all stored procedures, views, functions, and triggers for a text fragment (e.g. a table name or business term). Useful for impact analysis and legacy code exploration.

Analyze index usage (seeks/scans/lookups/updates per index) and list potentially missing indexes suggested by the query optimizer. Optionally filter usage stats by table name.

Analyze storage: largest tables by size (row count, total/used MB) and database file sizes. Useful for capacity planning and finding space hogs.

Analyze index fragmentation and recommend maintenance: REBUILD (fragmentation ≥ 30%), REORGANIZE (5–30%), or OK (< 5%). Generates ready-to-run ALTER INDEX statements (ONLINE=ON suggested automatically on editions that support it). Small indexes below minPageCount are excluded since fragmentation there is harmless.

Find the most expensive queries from the plan cache, ranked by a chosen metric: cpu, duration, reads (logical I/O), writes, memory (grant size), or executions. Returns per-query totals and averages with the SQL text — the starting point for performance tuning.

Overall performance health check: top wait statistics (with benign waits filtered out), memory counters (Page Life Expectancy, memory grants pending, total vs target memory), workload counters (batch requests, compilations), and rule-based optimization recommendations (e.g. high CXPACKET → review MAXDOP, PAGEIOLATCH → check I/O and indexes, LCK_M → run mssql_find_blocking).

Find current blocking chains: which sessions are blocked, by whom, on what resource, and for how long. Identifies lead blockers (including idle sessions holding open transactions) with their SQL text. Supported: SQL Server 2019 (15.x), 2022 (16.x), 2025 (17.x) — all editions including Express. Requires VIEW SERVER STATE.

Retrieve recent deadlock events from the built-in system_health Extended Events session, including the full deadlock graph XML, victim sessions, and the queries involved. Source 'ring_buffer' (default, fast, recent events only) or 'file' (reads system_health .xel files, further back but slower). Supported: SQL Server 2019 (15.x), 2022 (16.x), 2025 (17.x) — all editions including Express. Requires VIEW SERVER STATE.