MsSqlMCP

MCP Server for SQL Server database schema inspection and read-only query execution.

Features

Read-only access: All queries are validated to prevent data modification (INSERT, UPDATE, DELETE, DROP, EXEC, etc. are blocked)
Schema discovery: Tables, columns, relationships, and stored procedures
SQL execution: Safe SELECT queries only
Dual transport: Supports both stdio and HTTP/SSE protocols
Windows Service: Can run as a Windows Service for production deployments
MCP Protocol: Compatible with VS Code Copilot, Claude Desktop, and other MCP clients

Prerequisites

.NET 10 (or .NET 9 with minor adjustments)
SQL Server

Architecture

The project follows SOLID principles with dependency injection:

code

MsSqlMCP/
├── Program.cs                    # Entry point with DI and dual transport
├── SchemaTool.cs                 # MCP tool definitions
├── Interfaces/
│   ├── IConnectionFactory.cs     # SQL connection abstraction
│   ├── IQueryExecutor.cs         # Query execution abstraction
│   ├── ISchemaRepository.cs      # Schema queries abstraction
│   └── ISqlQueryValidator.cs     # Query validation abstraction
├── Services/
│   ├── SqlConnectionFactory.cs   # Connection management
│   ├── SafeQueryExecutor.cs      # Validated query execution
│   ├── SchemaRepository.cs       # Schema query implementation
│   └── ReadOnlySqlQueryValidator.cs # Security validation (27 blocked keywords)
└── Tests/
    └── ReadOnlySqlQueryValidatorTests.cs # 42 security tests

Configuration

Connection String

Edit appsettings.json:

json

{
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=(local);Initial Catalog=YourDatabase;Encrypt=False;Trusted_Connection=True;MultipleActiveResultSets=true"
  },
  "Urls": "http://localhost:5000"
}

Running

Console Mode (Development)

bash

# Run with both stdio and HTTP transports
dotnet run

# Run with HTTP transport only (for debugging)
dotnet run -- --http-only

Run Tests

bash

dotnet test --filter "FullyQualifiedName~Tests"

MCP Client Configuration

Option 1: stdio Transport (VS Code)

Add to your VS Code settings.json:

json

{
  "mcp": {
    "servers": {
      "MsSqlMCP": {
        "type": "stdio",
        "command": "dotnet",
        "args": ["run", "--project", "c:\\path\\to\\MsSqlMCP.csproj"]
      }
    }
  }
}

Option 2: HTTP Transport (VS Code)

First, start the server:

bash

dotnet run -- --http-only

Then add to your VS Code settings.json:

json

{
  "mcp": {
    "servers": {
      "MsSqlMCP": {
        "type": "http",
        "url": "http://localhost:5000/sse",
        "autoApprove": [
          "get_tables",
          "get_columns", 
          "get_relationships",
          "execute_sql",
          "get_store_procedure"
        ]
      }
    }
  }
}

Option 3: Claude Desktop

Add to claude_desktop_config.json:

json

{
  "mcpServers": {
    "MsSqlMCP": {
      "command": "dotnet",
      "args": ["run", "--project", "c:\\path\\to\\MsSqlMCP.csproj"]
    }
  }
}

Available Tools

Tool	Description	Required Parameters
`GetTables`	Get all table names in the database	None
`GetColumns`	Get columns (fields) for a specific table	`tableName`
`GetRelationships`	Get foreign key relationships between tables	None
`GetStoreProcedure`	Get stored procedure definition	`spName`
`ExecuteSql`	Execute a read-only SELECT query	`sqlQuery`

All tools accept an optional databaseName parameter to query different databases in the same SQL Server instance.

Security

The ExecuteSql tool only allows SELECT queries. The following statements are blocked:

DML: INSERT, UPDATE, DELETE, MERGE, TRUNCATE
DDL: CREATE, ALTER, DROP
DCL: GRANT, REVOKE, DENY
Execution: EXEC, EXECUTE, SP_EXECUTESQL, XP_
Others: BACKUP, RESTORE, BULK, OPENROWSET, OPENQUERY, OPENDATASOURCE

Windows Service Installation

1. Publish the Application

On your development machine:

bash

cd c:\path\to\MsSqlMCP
dotnet publish -c Release -r win-x64 --self-contained true

This creates files in: bin\Release\net10.0\win-x64\publish\

2. Copy to Server

Copy the contents of the publish folder to the server:

code

Source: bin\Release\net10.0\win-x64\publish\*
Destination: C:\Services\MsSqlMCP\

3. Configure on Server

Edit C:\Services\MsSqlMCP\appsettings.json with your SQL Server connection string:

json

{
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=YOUR_SQL_SERVER;Initial Catalog=YOUR_DATABASE;Encrypt=False;Trusted_Connection=True;MultipleActiveResultSets=true"
  },
  "Urls": "http://localhost:5000"
}

4. Install the Service

Open PowerShell as Administrator and run:

powershell

# Create the Windows Service
sc.exe create MsSqlMCP binPath= "C:\Services\MsSqlMCP\MsSqlMCP.exe --http-only" start= auto DisplayName= "MsSql MCP Server"

# Add description
sc.exe description MsSqlMCP "Model Context Protocol server for SQL Server database inspection"

# Create logs directory
mkdir C:\Services\MsSqlMCP\logs -Force

# Start the service
net start MsSqlMCP

# Verify status
sc.exe query MsSqlMCP

5. Verify Installation

powershell

# Check service status
Get-Service -Name MsSqlMCP

# Test the endpoint
Invoke-RestMethod -Uri "http://localhost:5000/sse/tools"

Service Management Commands

powershell

# Stop service
net stop MsSqlMCP

# Start service
net start MsSqlMCP

# Restart service
net stop MsSqlMCP; net start MsSqlMCP

# Uninstall service
net stop MsSqlMCP
sc.exe delete MsSqlMCP

Firewall Configuration (if accessing remotely)

powershell

# Allow inbound traffic on port 5000
New-NetFirewallRule -DisplayName "MsSqlMCP" -Direction Inbound -Port 5000 -Protocol TCP -Action Allow

HTTP API Endpoints

When running in HTTP mode, the following endpoints are available:

Endpoint	Method	Description
`/sse`	GET	SSE stream for MCP protocol
`/sse/tools`	GET	List all available tools
`/sse/invoke`	POST	Invoke a tool

Example: Invoke Tool via HTTP

bash

curl -X POST http://localhost:5000/sse/invoke \
  -H "Content-Type: application/json" \
  -d '{"Tool": "GetTables", "Params": {}}'

powershell

Invoke-RestMethod -Uri "http://localhost:5000/sse/invoke" -Method POST -ContentType "application/json" -Body '{"Tool": "GetTables", "Params": {}}'

Troubleshooting

Service won't start

1. Check logs in C:\Services\MsSqlMCP\logs\

2. Verify connection string in appsettings.json

3. Ensure SQL Server is accessible from the service account

4. Run manually to see errors: C:\Services\MsSqlMCP\MsSqlMCP.exe --http-only

Connection issues

1. Verify SQL Server is running

2. Check firewall rules for SQL Server port (1433)

3. If using Windows Authentication, ensure the service account has database access

Port already in use

Change the port in appsettings.json:

json

{
  "Urls": "http://localhost:5001"
}

License

MIT

Mssqlmcp

Documentation

MsSqlMCP

Features

Prerequisites

Architecture

Configuration

Connection String

Running

Console Mode (Development)

Run Tests

MCP Client Configuration

Option 1: stdio Transport (VS Code)

Option 2: HTTP Transport (VS Code)

Option 3: Claude Desktop

Available Tools

Security

Windows Service Installation

1. Publish the Application

2. Copy to Server

3. Configure on Server

4. Install the Service

5. Verify Installation

Service Management Commands

Firewall Configuration (if accessing remotely)

HTTP API Endpoints

Example: Invoke Tool via HTTP

Troubleshooting

Service won't start

Connection issues

Port already in use

License

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