dotnet-sqlserver-mcp

brendankowitz/dotnet-sqlserver-mcp

3.3

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A .NET-based Model Context Protocol (MCP) server providing essential tools for SQL Server database inspection, querying, and debugging.

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SQL Server MCP Server

A .NET-based Model Context Protocol (MCP) server providing 6 essential tools for SQL Server database inspection, querying, and debugging.

NuGet

Quick Start

Install as .NET Tool (Recommended)

dotnet tool install --global SqlServerLocalMcp

Then configure in Claude Desktop (see configuration below).

Or Build from Source

cd SqlServerMcp
dotnet build

Test Locally

export SQL_SERVER_CONNECTION_STRING="Server=localhost;Database=MyDB;Trusted_Connection=True;TrustServerCertificate=True;"
dotnet run

Setup for Claude Desktop

Edit the config file for your platform:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json

Option 1: Using Installed .NET Tool (Recommended)

{
  "mcpServers": {
    "sqlserver": {
      "command": "sqlserverlocal-mcp",
      "args": [],
      "env": {
        "SQL_SERVER_CONNECTION_STRING": "Server=localhost;Database=MySqlDb;Trusted_Connection=True;TrustServerCertificate=True;"
      }
    }
  }
}

Option 2: Running from Source

{
  "mcpServers": {
    "sqlserver": {
      "command": "dotnet",
      "args": ["run", "--project", "C:\\src\\dotnet-sqlserver-mcp\\SqlServerMcp"],
      "env": {
        "SQL_SERVER_CONNECTION_STRING": "Server=localhost;Database=MySqlDb;Trusted_Connection=True;TrustServerCertificate=True;"
      }
    }
  }
}

Important:

  • Use absolute paths
  • Windows: Use \\ for backslashes or / for forward slashes
  • macOS/Linux: Use forward slashes
  • Restart Claude Desktop after editing

Setup for Claude CLI (Code Editor)

Option 1: Using Installed .NET Tool (Recommended)

claude mcp add --transport stdio sqlserver \
  --env SQL_SERVER_CONNECTION_STRING="Server=localhost;Database=MySqlDb;Trusted_Connection=True;TrustServerCertificate=True;" \
  -- sqlserverlocal-mcp

Option 2: Running from Source

Windows:

claude mcp add --transport stdio sqlserver ^
  --env SQL_SERVER_CONNECTION_STRING="Server=localhost;Database=MySqlDb;Trusted_Connection=True;TrustServerCertificate=True;" ^
  -- cmd /c dotnet run --project C:\src\dotnet-sqlserver-mcp\SqlServerMcp

macOS/Linux:

claude mcp add --transport stdio sqlserver \
  --env SQL_SERVER_CONNECTION_STRING="Server=localhost;Database=MySqlDb;Trusted_Connection=True;TrustServerCertificate=True;" \
  -- dotnet run --project /path/to/dotnet-sqlserver-mcp/SqlServerMcp

With additional options:

claude mcp add --transport stdio sqlserver \
  --env SQL_SERVER_CONNECTION_STRING="Server=localhost;Database=MyDB;Trusted_Connection=True;" \
  --env SQL_SERVER_READONLY="true" \
  --env SQL_SERVER_MAX_ROWS="500" \
  -- dotnet run --project /path/to/SqlServerMcp

Management commands:

claude mcp list              # List all servers
claude mcp get sqlserver     # View server details
claude mcp remove sqlserver  # Remove server

Connection Strings

TypeExample
Windows AuthServer=localhost;Database=MyDB;Trusted_Connection=True;TrustServerCertificate=True;
SQL AuthServer=localhost;Database=MyDB;User Id=sa;Password=Pass123;TrustServerCertificate=True;
Azure SQLServer=myserver.database.windows.net;Database=MyDB;User Id=user;Password=Pass123;Encrypt=true;
LocalDBServer=(localdb)\\\\mssqllocaldb;Database=MyDB;Trusted_Connection=True;

Configuration Options

Add to the env section:

VariableDefaultDescription
SQL_SERVER_CONNECTION_STRINGrequiredConnection string
SQL_SERVER_READONLYtrueBlock INSERT/UPDATE/DELETE
SQL_SERVER_MAX_ROWS1000Max rows returned
SQL_SERVER_DEFAULT_TIMEOUT30Query timeout (seconds)
SQL_SERVER_ALLOW_PROCEDURE_EXECUTIONfalseAllow stored procedures
SQL_SERVER_ALLOWED_PROCEDURES``Allowed procedures (e.g., dbo.Get*,reporting.*)
SQL_SERVER_ALLOW_FUNCTION_EXECUTIONtrueAllow functions

Example with options:

{
  "mcpServers": {
    "sqlserver": {
      "command": "dotnet",
      "args": ["run", "--project", "C:\\src\\dotnet-sqlserver-mcp\\SqlServerMcp"],
      "env": {
        "SQL_SERVER_CONNECTION_STRING": "Server=localhost;Database=MyDB;Trusted_Connection=True;TrustServerCertificate=True;",
        "SQL_SERVER_READONLY": "true",
        "SQL_SERVER_MAX_ROWS": "500",
        "SQL_SERVER_ALLOW_PROCEDURE_EXECUTION": "true",
        "SQL_SERVER_ALLOWED_PROCEDURES": "dbo.GetOrders,reporting.*"
      }
    }
  }
}

Available Tools (6)

Core Essential Tools

ToolPurposeUnique Value
execute_sqlRun any SQL queryUniversal workhorse - handles custom queries, aggregations, metadata inspection
describe_tableInspect table schemaClean formatted output for columns, indexes, constraints in one call
get_procedure_definitionView stored proc sourceClean T-SQL source code without metadata noise
list_stored_proceduresFind available procsQuick filtered list with creation/modification dates
get_query_statsPerformance debuggingPre-formatted top queries by CPU/duration/execution count
get_connectionsConnection monitoringActive sessions with program names and login times

Usage Examples

Ask:

  • "List all tables in my database" → Uses execute_sql with INFORMATION_SCHEMA query
  • "Describe the Orders table structure" → Uses describe_table
  • "What foreign keys reference the Customers table?" → Uses execute_sql with sys.foreign_keys query
  • "Show me the top 10 slowest queries" → Uses get_query_stats
  • "Find duplicate email addresses in the Users table" → Uses execute_sql with GROUP BY/HAVING
  • "Show me the code for the GetCustomerOrders stored procedure" → Uses get_procedure_definition

Security

Read-Only Mode (Default): Only SELECT queries allowed. Set SQL_SERVER_READONLY=false to allow modifications.

Stored Procedures: Require SQL_SERVER_ALLOW_PROCEDURE_EXECUTION=true and optional allowlist.

Adjust limits:

"env": {
  "SQL_SERVER_MAX_ROWS": "100",
  "SQL_SERVER_DEFAULT_TIMEOUT": "60"
}

Project Structure

SqlServerMcp/
├── Program.cs              # Entry point
├── Configuration/          # Config models
├── Models/                 # Data models
├── Services/              # SqlService, ResultFormatter
└── Tools/                 # 4 tool classes (6 essential tools)
    ├── QueryTools.cs       # execute_sql
    ├── SchemaTools.cs      # describe_table, list_stored_procedures
    ├── DiagnosticTools.cs  # get_connections, get_query_stats
    └── ProcedureTools.cs   # get_procedure_definition

Development

Add new tools: Create methods in Tools/*.cs with [McpServerTool] attribute:

[McpServerTool]
[Description("Your tool description")]
public async Task<string> YourTool(
    [Description("Parameter description")] string parameter)
{
    // Implementation
}

Test with MCP Inspector:

npx @modelcontextprotocol/inspector dotnet run --project SqlServerMcp

Requirements

  • .NET 8 SDK
  • SQL Server (local, Azure SQL, or Docker)
  • Claude Desktop or Claude CLI

License

See file.

Resources