Microsoft SQL Server MCP Server

io.github.alyiox/mcp-mssql

Repository Registry

What is the Microsoft SQL Server MCP server?

Read-only-by-default SQL Server: schema, parameterized SELECT, execution plans; writes opt-in.

How to install Microsoft SQL Server

Copy-paste configuration for popular MCP clients.

transport: stdio

Config generated by PluginBench — verify against the source before use.

Environment / auth

MCPMSSQL_CONNECTION_STRING
secret
Default profile SQL Server connection string (often contains secrets). Optional if profiles are only in user appsettings.
MCPMSSQL_DESCRIPTION
Optional human-readable description for the default profile.
MCPMSSQL_QUERY_MAX_ROWS
Max rows per interactive query (default 500; ceiling 1000).
MCPMSSQL_QUERY_COMMAND_TIMEOUT_SECONDS
Interactive query command timeout in seconds (default 30).
MCPMSSQL_QUERY_SNAPSHOT_MAX_ROWS
Max rows for snapshot queries (default 10000; ceiling 50000).
MCPMSSQL_QUERY_SNAPSHOT_COMMAND_TIMEOUT_SECONDS
Snapshot query timeout in seconds (default 120).
MCPMSSQL_ANALYZE_COMMAND_TIMEOUT_SECONDS
Execution plan analysis timeout in seconds (default 300; ceiling 600).
MCPMSSQL_ALLOW_WRITE
Enable write commands (DDL/DML) via run_command on the default profile (default false). With no write-enabled profile the tool is not advertised at all. Soft guard only — prefer a db_datareader login for a hard read-only guarantee.
MCPMSSQL_WRITE_COMMAND_TIMEOUT_SECONDS
Write command timeout in seconds (default 60; ceiling 600).
DOTNET_ENVIRONMENT
Set to Development to load dotnet user-secrets (local dev).

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "mcp-mssql": {
      "command": "dnx",
      "args": [
        "Alyio.McpMssql"
      ],
      "env": {
        "MCPMSSQL_CONNECTION_STRING": "<YOUR_MCPMSSQL_CONNECTION_STRING>",
        "MCPMSSQL_DESCRIPTION": "<YOUR_MCPMSSQL_DESCRIPTION>",
        "MCPMSSQL_QUERY_MAX_ROWS": "<YOUR_MCPMSSQL_QUERY_MAX_ROWS>",
        "MCPMSSQL_QUERY_COMMAND_TIMEOUT_SECONDS": "<YOUR_MCPMSSQL_QUERY_COMMAND_TIMEOUT_SECONDS>",
        "MCPMSSQL_QUERY_SNAPSHOT_MAX_ROWS": "<YOUR_MCPMSSQL_QUERY_SNAPSHOT_MAX_ROWS>",
        "MCPMSSQL_QUERY_SNAPSHOT_COMMAND_TIMEOUT_SECONDS": "<YOUR_MCPMSSQL_QUERY_SNAPSHOT_COMMAND_TIMEOUT_SECONDS>",
        "MCPMSSQL_ANALYZE_COMMAND_TIMEOUT_SECONDS": "<YOUR_MCPMSSQL_ANALYZE_COMMAND_TIMEOUT_SECONDS>",
        "MCPMSSQL_ALLOW_WRITE": "<YOUR_MCPMSSQL_ALLOW_WRITE>",
        "MCPMSSQL_WRITE_COMMAND_TIMEOUT_SECONDS": "<YOUR_MCPMSSQL_WRITE_COMMAND_TIMEOUT_SECONDS>",
        "DOTNET_ENVIRONMENT": "<YOUR_DOTNET_ENVIRONMENT>"
      }
    }
  }
}