MCP SQL Server Tool

A read-only Model Context Protocol (MCP) server for Microsoft SQL Server that supports metadata discovery, parameterized queries, and query analysis, with profile-based configuration and strict no-DML/DDL enforcement.

Requirements: .NET 10.0 SDK, SQL Server, and a connection string.

Quick start

Set MCPMSSQL_CONNECTION_STRING and run the server in one of these ways:

# Option 1: Run from NuGet package (e.g. with MCP Inspector)
export MCPMSSQL_CONNECTION_STRING="Server=127.0.0.1;User ID=sa;Password=<YourStrong@Passw0rd>;Encrypt=True;TrustServerCertificate=True;"
npx -y @modelcontextprotocol/inspector dotnet dnx Alyio.McpMssql --prerelease

# Option 2: Install and run as a global tool
dotnet tool install --global Alyio.McpMssql --prerelease
export MCPMSSQL_CONNECTION_STRING="Server=127.0.0.1;User ID=sa;Password=<YourStrong@Passw0rd>;Encrypt=True;TrustServerCertificate=True;"
npx -y @modelcontextprotocol/inspector mcp-mssql

# Option 3: Run from source (clone repo, then)
export MCPMSSQL_CONNECTION_STRING="Server=127.0.0.1;User ID=sa;Password=<YourStrong@Passw0rd>;Encrypt=True;TrustServerCertificate=True;"
npx -y @modelcontextprotocol/inspector dotnet run --project src/Alyio.McpMssql

Use --prerelease for pre-release builds.

Configuration

All settings use the MCPMSSQL prefix. Flat environment variables (e.g. MCPMSSQL_CONNECTION_STRING) are the straightforward way to configure the default profile when you have a single connection. For multiple profiles, the user-scoped appsettings.json file is recommended.

Single connection: Configure via environment variables.

# Connection string (required).
export MCPMSSQL_CONNECTION_STRING="Server=127.0.0.1;User ID=sa;Password=<YourStrong@Passw0rd>;Encrypt=True;TrustServerCertificate=True;"

# Optional description for the default profile (tooling/AI discovery).
export MCPMSSQL_DESCRIPTION="Primary connection"

# Optional max rows per interactive query (default `500`; hard ceiling `1000`).
export MCPMSSQL_QUERY_MAX_ROWS="500"

# Optional query timeout in seconds (default `30`).
export MCPMSSQL_QUERY_COMMAND_TIMEOUT_SECONDS="60"

# Optional max rows for snapshot queries (default `10000`; hard ceiling `50000`).
export MCPMSSQL_QUERY_SNAPSHOT_MAX_ROWS="10000"

# Optional snapshot query timeout in seconds (default `120`).
export MCPMSSQL_QUERY_SNAPSHOT_COMMAND_TIMEOUT_SECONDS="120"

# Optional analyze timeout in seconds (default `300`).
export MCPMSSQL_ANALYZE_COMMAND_TIMEOUT_SECONDS="300"

Multiple connections: Use the user-scoped appsettings.json file (recommended). Env vars also work via .NET host conventions (MCPMSSQL__PROFILES__<NAME>__CONNECTIONSTRING, etc.).

• Unix-like: ~/.config/mcp-mssql/appsettings.json
• Windows: %USERPROFILE%\.config\mcp-mssql\appsettings.json

Example (appsettings.json):

{
  "McpMssql": {
    "Profiles": {
      "default": {
        "ConnectionString": "Server=...;User ID=...;Password=...;",
        "Description": "Primary connection",
        "Query": {
          "MaxRows": 500,
          "CommandTimeoutSeconds": 60,
          "SnapshotMaxRows": 10000,
          "SnapshotCommandTimeoutSeconds": 120
        },
        "Analyze": {
          "CommandTimeoutSeconds": 300
        }
      },
      "warehouse": {
        "ConnectionString": "Server=warehouse.example.com;...",
        "Description": "Warehouse read-only"
      }
    }
  }
}

Local development: Store the connection string in user-secrets, then run with DOTNET_ENVIRONMENT=Development so secrets load.

do

... [View full README on GitHub](https://github.com/alyiox/mcp-mssql#readme)