slyderc/climate_mssql_mcp

Climate MSSQL MCP Server

A lightweight, reliable Model Context Protocol (MCP) server for Microsoft SQL Server using Python and pymssql.

Why This MCP Server?

Built from frustration with connection issues in Node.js-based MSSQL MCP servers, this Python implementation uses the proven pymssql library for rock-solid SQL Server connectivity. No mysterious timeouts, no complex configuration - just working database access.

Prerequisites

• Python 3.10 or higher
• uv (recommended) or pip
• Access to a Microsoft SQL Server instance
• Claude Code or any MCP-compatible client

Quick Start

1. Clone or Download

git clone https://github.com/yourusername/climate_mssql_mcp.git
cd climate_mssql_mcp

2. Make the Server Executable

chmod +x server.py

That's it! The server uses uv with inline dependencies - no separate installation needed.

Configuration for Claude Code

Add this to your project's .mcp.json file:

{
  "mcpServers": {
    "MSSQL-MCP": {
      "command": "/absolute/path/to/climate_mssql_mcp/server.py",
      "env": {
        "SERVER_NAME": "your-server.domain.com\\SQLEXPRESS",
        "PORT": "1433",
        "DATABASE_NAME": "YourDatabase",
        "SQL_USERNAME": "your-username",
        "SQL_PASSWORD": "your-password",
        "READONLY": "false"
      },
      "type": "stdio"
    }
  }
}

Configuration Options

Connection Behavior:

• Connection timeout: 30 seconds (network operations)
• Login timeout: 15 seconds (authentication)
• Connections are opened per-operation and closed immediately after (no pooling)

Connection String Format

For named instances (like SQLEXPRESS), use double backslashes in JSON:

"SERVER_NAME": "hostname\\SQLEXPRESS"

For default instances or IP addresses:

"SERVER_NAME": "hostname.domain.com"

or

"SERVER_NAME": "192.168.1.100"

Available Tools

Read Operations (Always Available)

list_table

List all tables in the database or filter by schema.

Parameters:

• parameters (optional): Array of schema names to filter by

Example:

List all tables in dbo schema

describe_table

Show the schema/structure of a specific table.

Parameters:

• tableName (required): Name of the table

Example:

Describe the Media table

read_data

Execute SELECT queries against the database.

Parameters:

• query (required): SQL SELECT statement

Example:

Show me the top 10 artists from the Artists table

Write Operations (When READONLY=false)

insert_data

Insert one or more records into a table.

Parameters:

• tableName (required): Target table name
• data (required): Single object or array of objects with column:value pairs

update_data

Update records in a table.

Parameters:

• tableName (required): Target table name
• updates (required): Object with column:value pairs to update
• whereClause (required): WHERE condition (without the "WHERE" keyword)

create_table

Create a new table.

Parameters:

• tableName (required): Name for new table
• columns (required): Array of column definitions with name, type, nullable, primaryKey

create_index

Create an index on a table.

Parameters:

• tableName (required): Table to index
• indexName (required): Name for the index
• columns (required): Array of column names
• unique (optional): true for unique index

drop_table

Delete a table from the database.

Parameters:

• tableName (required): Table to drop

Usage in Claude Code

Once configured, simply ask Claude to interact with your database:

What tables are in the database?

Show me the schema of the Media table

Find all artists with names starting with 'The'

Create a test table called temp_data with id and name columns

Claude will automatically use the appropriate MCP tools to execute your requests.

Troubleshooting

Connection Fails

• Verify SQL Server is running and accessible
• Check firewall rules allow connections on the specified port
• Confirm SQL Server authentication is enabled (not just Windows auth)
• Test connection with a SQL client (Azure Data Studio, SSMS) using the same credentials

Timeout Errors

• Connection attempts timeout after 15 seconds (login) or 30 seconds (operations)
• If you see timeout errors on a known-working server, check network latency
• For slow networks, you may need to adjust timeout values in server.py:39-40

Permission Errors

• Ensure the SQL user has appropriate permissions on the target database
• For write operations, user needs INSERT/UPDATE/DELETE/CREATE/DROP permissions

Module Import Errors

If you see import errors, ensure uv is installed:

curl -LsSf https://astral.sh/uv/install.sh | sh

Security Notes

• Never commit .mcp.json with real credentials to version control
• Use environment variables or secure credential storage for production
• Consider using read-only mode (READONLY: "true") when write access isn't needed
• Restrict SQL user permissions to minimum required for your use case

Technical Details

• Language: Python 3.10+
• Database Driver: pymssql 2.2.0+
• MCP Protocol: Model Context Protocol 0.1.0+
• Dependency Management: uv (inline script dependencies)

License

MIT License - see file for details.

Contributing

Issues and pull requests welcome! This project prioritizes simplicity and reliability over features.

Acknowledgments

Built as a pragmatic alternative to Node.js MSSQL MCP implementations, proving that sometimes the best solution is the simplest one.