SQL Server MCP Client

A comprehensive Microsoft SQL Server client implementing the Model Context Protocol (MCP). This server provides extensive SQL Server capabilities including query execution, schema discovery, and stored procedure management through a simple MCP interface.

Overview

The SQL Server MCP client is built with .NET Core using the Model Context Protocol C# SDK (github.com/modelcontextprotocol/csharp-sdk). It provides tools for executing SQL queries, managing stored procedures, listing tables, and retrieving comprehensive schema information from SQL Server databases. The server is designed to be lightweight yet powerful, demonstrating how to create a robust MCP server with practical database functionality. It can be deployed either directly on a machine or as a Docker container.

The MCP client operates in one of two modes:

• Database Mode: When a specific database is specified in the connection string, only operations within that database context are available
• Server Mode: When no database is specified in the connection string, server-wide operations across all databases are available

Features

Core Database Operations

• Execute SQL queries on connected SQL Server databases
• List all tables with schema and row count information
• Retrieve detailed schema information for specific tables
• Comprehensive stored procedure management and execution

Advanced Tools

• Export/import tables as CSV
• Paginated and streaming query support
• Index, view, and function metadata
• Script execution and discovery tools
• Cursor guidance for query navigation

Security & Configuration

• Configurable tool enablement for security
• Environment-based configuration
• Comprehensive error handling and validation

Getting Started

Prerequisites

• .NET 8.0 (for local development/deployment)
• Docker (for container deployment)

Build Instructions (for development)

1. Clone this repository:

git clone https://github.com/akashCF/dotnet-mssql-mcp.git

2. Navigate to the project root directory:

cd dotnet-mssql-mcp

3. Build the project using:

dotnet build src/mssqlclient.sln

Docker Support

Docker Hub

The SQL Server MCP Client is available on Docker Hub.

# Pull the latest version
docker pull akashcf/dotnet-mssql-mcp:latest

Manual Docker Build

If you need to build the Docker image yourself:

# Navigate to the repository root
cd dotnet-mssql-mcp

# Build the Docker image
docker build -f src/Core.Infrastructure.McpServer/Dockerfile -t dotnet-mssql-mcp:latest src/

# Run the locally built image
docker run -d --name mssql-mcp -e "MSSQL_CONNECTIONSTRING=Server=your_server;Database=your_db;User Id=your_user;Password=your_password;TrustServerCertificate=True;" dotnet-mssql-mcp:latest

MCP Protocol Usage

Client Integration

To connect to the SQL Server MCP Client from your applications:

1. Use the Model Context Protocol C# SDK or any MCP-compatible client

2. Configure your client to connect to the server's endpoint

3. Call the available tools described below

Available Tools

The available tools differ depending on which mode the server is operating in, with some tools available in both modes:

Common Tools (Both Modes)

server_capabilities

Returns detailed information about the capabilities and features of the connected SQL Server instance.

Example request:

{
  "name": "server_capabilities",
  "parameters": {}
}

Example response in Server Mode:

{
  "version": "Microsoft SQL Server 2019",
  "majorVersion": 15,
  "minorVersion": 0,
  "buildNumber": 4123,
  "edition": "Enterprise Edition",
  "isAzureSqlDatabase": false,
  "isAzureVmSqlServer": false,
  "isOnPremisesSqlServer": true,
  "toolMode": "server",
  "features": {
    "supportsPartitioning": true,
    "supportsColumnstoreIndex": true,
    "supportsJson": true,
    "supportsInMemoryOLTP": true,
    "supportsRowLevelSecurity": true,
    "supportsDynamicDataMasking": true,
    "supportsDataCompression": true,
    "supportsDatabaseSnapshots": true,
    "supportsQueryStore": true,
    "supportsResumableIndexOperations": true,
    "supportsGraphDatabase": true,
    "supportsAlwaysEncrypted": true,
    "supportsExactRowCount": true,
    "supportsDetailedIndexMetadata": true,
    "supportsTemporalTables": true
  }
}

This tool is useful for:

• Determining which features are available in your SQL Server instance
• Debugging compatibility issues
• Understanding which query patterns will be used
• Verifying whether you're in server or database mode

cursor_guide

Provides guidance for navigating large result sets using cursors.

Example request:

{
  "name": "cursor_guide",
  "parameters": { "query": "SELECT * FROM Orders" }
}

paginated_query

Executes a query and returns results in pages.

Example request:

{
  "name": "paginated_query",
  "parameters": { "query": "SELECT * FROM Orders", "page": 1, "pageSize": 100 }
}

query_streamer

Streams large query results in chunks.

Example request:

{
  "name": "query_streamer",
  "parameters": { "query": "SELECT * FROM Orders" }
}

export_table_csv

Exports a table to CSV format.

Example request:

{
  "name": "export_table_csv",
  "parameters": { "tableName": "Customers" }
}

import_table_csv

Imports data from a CSV file into a table.

Example request:

{
  "name": "import_table_csv",
  "parameters": { "tableName": "Customers", "csvData": "...csv content..." }
}

run_script

Executes a SQL script.

Example request:

{
  "name": "run_script",
  "parameters": { "script": "CREATE TABLE Test (Id INT)" }
}

discover

Discovers schema, tables, and other metadata.

Example request:

{
  "name": "discover",
  "parameters": {}
}

Server Mode Tools (No Database in Connection String)

server_list_tables

Lists all tables in all databases.

Example request:

{
  "name": "server_list_tables",
  "parameters": { "databaseName": "Northwind" }
}

server_list_databases

Lists all databases on the server.

Example request:

{
  "name": "server_list_databases",
  "parameters": {}
}

server_get_table_schema

Gets the schema for a table in a specific database.

Example request:

{
  "name": "server_get_table_schema",
  "parameters": { "databaseName": "Northwind", "tableName": "Customers" }
}

server_list_stored_procedures

Lists all stored procedures in a database.

Example request:

{
  "name": "server_list_stored_procedures",
  "parameters": { "databaseName": "Northwind" }
}

server_get_stored_procedure_definition

Gets the SQL definition of a stored procedure in a database.

Example request:

{
  "name": "server_get_stored_procedure_definition",
  "parameters": { "databaseName": "Northwind", "procedureName": "GetCustomerOrders" }
}

server_get_stored_procedure_parameters

Gets parameter info for a stored procedure in a database.

Example request:

{
  "name": "server_get_stored_procedure_parameters",
  "parameters": { "databaseName": "Northwind", "procedureName": "CreateNewCustomer" }
}

server_execute_query

Executes a query in a specific database (if enabled).

Example request:

{
  "name": "server_execute_query",
  "parameters": { "databaseName": "Northwind", "query": "SELECT * FROM Customers" }
}

server_execute_stored_procedure

Executes a stored procedure in a specific database (if enabled).

Example request:

{
  "name": "server_execute_stored_procedure",
  "parameters": { "databaseName": "Northwind", "procedureName": "CreateNewCustomer", "parameters": { "CompanyName": "Acme Corp" } }
}

get_function_details

Returns metadata about functions in a database.

Example request:

{
  "name": "get_function_details",
  "parameters": { "databaseName": "Northwind" }
}

get_view_details

Returns metadata about views in a database.

Example request:

{
  "name": "get_view_details",
  "parameters": { "databaseName": "Northwind" }
}

get_index_details

Returns metadata about indexes in a database.

Example request:

{
  "name": "get_index_details",
  "parameters": { "databaseName": "Northwind" }
}

Database Mode Tools (Database in Connection String)

list_tables

Lists all tables in the connected database.

Example request:

{
  "name": "list_tables",
  "parameters": {}
}

get_table_schema

Gets the schema for a table in the connected database.

Example request:

{
  "name": "get_table_schema",
  "parameters": { "tableName": "Customers" }
}

list_stored_procedures

Lists all stored procedures in the connected database.

Example request:

{
  "name": "list_stored_procedures",
  "parameters": {}
}

get_stored_procedure_definition

Gets the SQL definition of a stored procedure in the connected database.

Example request:

{
  "name": "get_stored_procedure_definition",
  "parameters": { "procedureName": "GetCustomerOrders" }
}

get_stored_procedure_parameters

Gets parameter info for a stored procedure in the connected database.

Example request:

{
  "name": "get_stored_procedure_parameters",
  "parameters": { "procedureName": "CreateNewCustomer" }
}

execute_query

Executes a query in the connected database (if enabled).

Example request:

{
  "name": "execute_query",
  "parameters": { "query": "SELECT * FROM Customers" }
}

execute_stored_procedure

Executes a stored procedure in the connected database (if enabled).

Example request:

{
  "name": "execute_stored_procedure",
  "parameters": { "procedureName": "CreateNewCustomer", "parameters": { "CompanyName": "Acme Corp" } }
}

Solution Structure

• src/mssqlclient.sln: Main solution file.
• Core.Infrastructure.McpServer/: Main server implementation and entry point (Program.cs).
• Core.Application/: Core application logic and interfaces.
• Core.Infrastructure.SqlClient/: SQL Server-specific data access and services.
• UnitTests.Infrastructure.McpServer/, UnitTests.Infrastructure.SqlClient/: Unit tests for server and SQL client logic.
• scripts/: Utility scripts for versioning and maintenance.
• cleanup-tools.sh, cleanup-tools.bat: Scripts to clean up build artifacts and tools.

Utility Scripts

• scripts/create-version.ps1: PowerShell script for version management.
• cleanup-tools.sh, cleanup-tools.bat: Clean up build artifacts and temporary files.

Configuration

Tool Security Configuration

The server provides granular control over which potentially dangerous operations are available:

Query Execution Security

By default, SQL query execution tools are disabled for security reasons. To enable these tools, set the EnableExecuteQuery configuration setting to true.

Stored Procedure Execution Security

By default, stored procedure execution tools are disabled for security reasons. To enable these tools, set the EnableExecuteStoredProcedure configuration setting to true.

These can be configured in several ways:

1. In the appsettings.json file:

{
  "EnableExecuteQuery": true,
  "EnableExecuteStoredProcedure": true
}

2. As environment variables when running the container:

docker run \
  -e "EnableExecuteQuery=true" \
  -e "EnableExecuteStoredProcedure=true" \
  -e "MSSQL_CONNECTIONSTRING=Server=your_server;..." \
  akashcf/dotnet-mssql-mcp:latest

3. In the Claude Desktop configuration:

"mssql": {
  "command": "dotnet",
  "args": [
    "YOUR_PATH_TO_DLL\\Core.Infrastructure.McpServer.dll"
  ],
  "env": {
    "MSSQL_CONNECTIONSTRING": "Server=your_server;...",
    "EnableExecuteQuery": "true",
    "EnableExecuteStoredProcedure": "true"
  }
}

4. In the VSCode configuration:

"mssql": {
  "type": "stdio",
  "command": "dotnet",
  "args": [
      "exec",
      "YOUR_PATH_TO_DLL/bin/Debug/net8.0/Core.Infrastructure.McpServer.dll"
  ],
  "env":{ 
      "MSSQL_CONNECTIONSTRING": "Data Source=yourserver;Initial Catalog=databasename;uid=user;Password=*****;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"
  }
}

When these settings are false (the default), the respective execution tools will not be registered and will not be available to clients. This provides additional security layers when you only want to allow read-only operations.

Database Connection String

The SQL Server connection string is required to connect to your database. This connection string should include server information, authentication details, and any required connection options.

You can set the connection string using the MSSQL_CONNECTIONSTRING environment variable:

# Database Mode with both execution types enabled
docker run \
  -e "EnableExecuteQuery=true" \
  -e "EnableExecuteStoredProcedure=true" \
  -e "MSSQL_CONNECTIONSTRING=Server=your_server;Database=your_db;User Id=your_user;Password=your_password;TrustServerCertificate=True;" \
  akashcf/dotnet-mssql-mcp:latest

# Server Mode with both execution types enabled
docker run \
  -e "EnableExecuteQuery=true" \
  -e "EnableExecuteStoredProcedure=true" \
  -e "MSSQL_CONNECTIONSTRING=Server=your_server;User Id=your_user;Password=your_password;TrustServerCertificate=True;" \
  akashcf/dotnet-mssql-mcp:latest

Server Mode vs Database Mode

The MCP server automatically detects the mode based on the connection string:

• Server Mode: When no database is specified in the connection string (no Database= or Initial Catalog= parameter)
• Database Mode: When a specific database is specified in the connection string

Example connection strings:

# Database Mode - Connects to specific database
Server=database.example.com;Database=Northwind;User Id=sa;Password=YourPassword;TrustServerCertificate=True;

# Server Mode - No specific database
Server=database.example.com;User Id=sa;Password=YourPassword;TrustServerCertificate=True;

# Database Mode with Windows Authentication
Server=database.example.com;Database=Northwind;Integrated Security=SSPI;TrustServerCertificate=True;

# Server Mode with specific port
Server=database.example.com,1433;User Id=sa;Password=YourPassword;TrustServerCertificate=True;

If no connection string is provided, the server will return an error message when attempting to use the tools.

Integrated security will not work from a docker container!

Configuring Claude Desktop

Using Local Installation

To configure Claude Desktop to use a locally installed SQL Server MCP client:

1. Add the server configuration to the mcpServers section in your Claude Desktop configuration:

"mssql": {
  "command": "dotnet",
  "args": [
    "YOUR_PATH_TO_DLL\\Core.Infrastructure.McpServer.dll"
  ],
  "env": {
    "MSSQL_CONNECTIONSTRING": "Server=your_server;Database=your_db;User Id=your_user;Password=your_password;TrustServerCertificate=True;",
    "EnableExecuteQuery": "true",
    "EnableExecuteStoredProcedure": "true"
  }
}

2. Save the file and restart Claude Desktop

Using Docker Container

To use the SQL Server MCP client from a Docker container with Claude Desktop:

1. Add the server configuration to the mcpServers section in your Claude Desktop configuration:

"mssql": {
  "command": "docker",
  "args": [
    "run",
    "--rm",
    "-i",
    "-e", "MSSQL_CONNECTIONSTRING=Server=your_server;Database=your_db;User Id=your_user;Password=your_password;TrustServerCertificate=True;",
    "-e", "EnableExecuteQuery=true",
    "-e", "EnableExecuteStoredProcedure=true",
    "akashcf/dotnet-mssql-mcp:latest"
  ]
}

2. Save the file and restart Claude Desktop

Architecture

Type System

The server includes a sophisticated type mapping system that converts JSON values to appropriate SQL Server types based on stored procedure parameter metadata:

• Automatic Type Detection: Uses SQL Server's sys.parameters metadata as the authoritative source
• Rich Type Support: Handles all major SQL Server data types including varchar, nvarchar, int, decimal, datetime, uniqueidentifier, etc.
• Validation: Provides detailed error messages for type mismatches and constraint violations
• Default Values: Supports parameters with default values and optional parameters

Parameter Handling

• Case-Insensitive: Parameter names are matched case-insensitively
• Flexible Naming: Supports both @ParameterName and ParameterName formats
• Normalization: Automatic parameter name normalization and validation
• JSON Schema: Generates JSON Schema compatible output for parameter validation

Security Model

The server implements a multi-layered security approach:

1. Tool-Level Security: Individual tools can be enabled/disabled

2. Parameter Validation: All inputs are validated against SQL Server metadata

3. SQL Injection Protection: Uses parameterized queries throughout

4. Connection Security: Supports all SQL Server authentication methods

License

This project is licensed under the MIT License - see the LICENSE file for details.