LabscoMCP early access ↗
alyioxMCP SERVER

SQL Server MCP

Query SQL Server read-only by default — SELECT with parameter binding, catalog metadata, execution-plan analysis — and unlock writes only on a profile you explicitly opt in.

by alyiox ↗Relational SQL DatabasesCommunity

LABSCO SUMMARY

Says plainly that its write lock is not a security boundary.

AllowWrite defaults to false and the write tool rejects at call time on locked profiles — but the README states outright that this is an application-level guard constraining the server, not the database, and points you at a db_datareader login for a real read-only guarantee. That honesty is worth more than the flag. Plan and snapshot resources expire on their own, at 7 days and 1 day, so nothing accumulates.

What it is

A .NET MCP server for Microsoft SQL Server built for safe exploration: metadata discovery, parameterized queries and query analysis, organised around named connection profiles. The query tools enforce SELECT-only with no DML or DDL, and the one tool that can write is rejected unless its profile opts in.

What you get

  • Configured connection profiles listed, so a multi-database setup is discoverable — list_profiles
  • Server properties and the live execution limits — timeouts, row caps, guardrails — get_server_properties
  • Catalog metadata by kind: databases, schemas, tables and views, procedures and functions — list_objects; and one relation or routine in detail with columns, indexes, constraints or definition — get_object
  • Read-only T-SQL executed with @paramName binding, returned as CSV inline (limit 500 rows, hard ceiling 1000) or as a snapshot resource for larger results — run_query
  • An execution plan summarised as compact JSON — cost, operators, cardinality, warnings, indexes, waits and stats — with the full XML fetched from plan_uri — analyze_query
  • Write T-SQL for profiles that set AllowWrite=true, returning rows_affected and server messages, marked destructive — run_command
  • The same data as browsable resources: mssql://profiles, mssql://server-properties, mssql://objects, plus mssql://plans/{id} (XML, expires after 7 days) and mssql://snapshots/{id} (CSV, expires after 1 day)

Requirements

A SQL Server instance and a connection string in MCPMSSQL_CONNECTION_STRING, plus a .NET 8.0 or later runtime for the global tool — it targets net8.0 and net10.0 — or the .NET 10 SDK for the client configurations, which launch it with dotnet dnx. Install it as a global tool with dotnet tool install --global Alyio.McpMssql --prerelease and run mcp-mssql over stdio; the published version is 1.2.0. For several databases, use the user-scoped appsettings.json under ~/.config/mcp-mssql/. Tunables are all MCPMSSQL_-prefixed environment variables: MCPMSSQL_QUERY_MAX_ROWS (default 500, ceiling 1000), MCPMSSQL_QUERY_COMMAND_TIMEOUT_SECONDS (default 30), MCPMSSQL_ALLOW_WRITE (default false). Azure SQL works through Microsoft Entra authentication modes set in the connection string. MIT licensed.

Setup effort

One command plus credentials — dotnet tool install --global Alyio.McpMssql --prerelease, then supply credentials

See installation options