SQL Server Read-Only MCP Server

A Model Context Protocol (MCP) server providing safe, read-only access to SQL Server and Azure SQL databases. This server enables AI assistants like Claude to explore database schemas, analyze performance, and execute queries without risk of data modification.

🎯 Purpose

This MCP server bridges the gap between AI assistants and SQL Server databases, providing comprehensive database exploration and analysis capabilities while maintaining strict read-only guarantees. Perfect for:

• Database exploration - Discover tables, views, functions, and stored procedures
• Performance analysis - Identify slow queries, locking issues, and missing indexes
• Schema understanding - Analyze relationships, dependencies, and security policies
• Query optimization - Examine execution plans without running queries
• Safe data access - Execute SELECT queries in controlled environments (full mode)

✨ Key Features

• 24 specialized MCP tools for comprehensive database interaction
• Two operation modes: Schema-only (default, maximum safety) and Full mode (query execution)
• Read-only enforcement at multiple layers (connection string, query validation, transaction rollback)
• Intelligent error handling with permission-specific guidance
• Performance tools including query plan analysis and locking diagnostics
• Zero data modification risk - all operations are strictly read-only

📋 Prerequisites

Required Software

1. .NET 10 SDK (or later)

   • Download from https://dotnet.microsoft.com/download/dotnet/10.0
   • Verify installation: dotnet --version

2. SQL Server or Azure SQL Database

   • SQL Server 2016+ or Azure SQL Database
   • Database user with read permissions (see Permissions)

3. MCP Client (one or more):

   • Claude Desktop app
   • Claude Code (VS Code extension)
   • Any MCP-compatible client

Permissions

The database user needs the following permissions for full functionality:

-- Minimum permissions (schema-only mode)
GRANT VIEW DEFINITION TO [your_user];
GRANT VIEW DATABASE STATE TO [your_user];
GRANT SELECT ON SCHEMA::dbo TO [your_user];

-- Optional for performance tools
GRANT VIEW SERVER STATE TO [your_user];

-- For specific system views
GRANT SELECT ON sys.tables TO [your_user];
GRANT SELECT ON sys.views TO [your_user];
GRANT SELECT ON sys.procedures TO [your_user];

🏗️ Building the Project

Clone the Repository

git clone <repository-url>
cd sqlserver-readonly-mcp

Build

# Standard build
dotnet build

# Release build for production
dotnet build -c Release

# Publish a self-contained executable
dotnet publish -c Release -r win-x64 --self-contained

The build output will be in:

• bin/Debug/net10.0/ for debug builds
• bin/Release/net10.0/ for release builds
• bin/Release/net10.0/win-x64/publish/ for published executables

🚀 Running the Server

Command-Line Usage

# Using environment variable (recommended)
export SQLSERVER_CONN_STR="Server=myserver;Database=mydb;User Id=readonly;Password=yourpassword;"
dotnet run

# Using command-line argument
dotnet run -- --connectionstring "Server=myserver;Database=mydb;User Id=readonly;Password=yourpassword;"

# Enable full mode (query execution)
dotnet run -- --schemaonly 0

# If you want to test (without running as MCP server)
dotnet ner -- --test --connectionstring "Server=myserver;Database=mydb;User Id=readonly;Password=yourpassword;"

# View help
dotnet run -- --help

Command-Line Options

... View full README on GitHub