SqlServerMcp

SqlServerMcp

A Model Context Protocol (MCP) server for SQL Server. Exposes schema inspection, safe read-only queries, and query plan analysis as MCP tools.

How it works: This server does not accept natural-language questions. Instead, the connected AI tool (the MCP client) decides and generates the SQL query based on the user's intent and the schema it inspects via the tools below. The server only executes the SQL the AI produces, under the safety rules described in Safety.

Install

dotnet tool install -g SqlServerMcp

Configure

Configuration is done entirely through environment variables in your MCP client config. No need to edit any files — just add your connection strings and query settings directly in the env block.

Add the following to your MCP client configuration (e.g. Claude Desktop claude_desktop_config.json):

{

"mcpServers": { "sqlserver": { "command": "sqlservermcp", "env": { "ConnectionStrings__MyDb": "Server=localhost;Database=MyDatabase;Trusted_Connection=True;TrustServerCertificate=True;", "QueryDefaultTop": "1000", "QueryMaxTop": "500000" } } } }

Environment Variable Format

Note: Use double underscores (__) as the separator — this is the .NET configuration convention for environment variables.

Multiple Databases

You can configure multiple databases by adding multiple connection string variables:

{

"env": { "ConnectionStringsProduction": "Server=prod-server;Database=ProdDb;...", "ConnectionStringsStaging": "Server=staging-server;Database=StagingDb;..." } }

Then use the ListDatabases tool to see available names, and pass the database name to any query tool.

Available Tools

Example

Prompt:

*"Using the MyDb database, show me the top 5 customers by total order amount in 2025."*

The AI generates and executes the query by calling SearchSchema / DescribeTable to discover the tables, then passing this SQL to RunQuery:

SELECT TOP 5 c.CustomerId, c.Name, SUM(o.TotalAmount) AS TotalSpent

FROM dbo.Customers c JOIN dbo.Orders o ON o.CustomerId = c.CustomerId WHERE YEAR(o.OrderDate) = 2025 GROUP BY c.CustomerId, c.Name ORDER BY TotalSpent DESC;

Expected output:

Disclaimer: The accuracy of the generated SQL and the final output depends on the AI model you select in your MCP client. More capable models produce more reliable queries; weaker models may misinterpret the schema or the intent of the prompt.

Safety

• Only SELECT queries are allowed — all write operations are blocked
• Queries are automatically row-limited to prevent runaway results
• Connection strings are configured server-side, never exposed to the AI client

License

MIT