legion mcp

A server that helps people access and query data in databases using the Legion Query Runner with integration of the Model Context Protocol (MCP) Python SDK.

Features

• Database access via Legion Query Runner
• Model Context Protocol (MCP) support for AI assistants
• Expose database operations as MCP resources, tools, and prompts
• Multiple deployment options (standalone MCP server, FastAPI integration)
• Query execution and result handling
• Flexible configuration via environment variables, command-line arguments, or MCP settings JSON

Supported Databases

We use Legion Query Runner library as connectors. You can find more info on their api doc.

What is MCP?

The Model Context Protocol (MCP) is a specification for maintaining context in AI applications. This server uses the MCP Python SDK to:

• Expose database operations as tools for AI assistants
• Provide database schemas and metadata as resources
• Generate useful prompts for database operations
• Enable stateful interactions with databases

Installation & Configuration

Required Parameters

Two parameters are required for all installation methods:

• DB_TYPE: The database type code (see table above)
• DB_CONFIG: A JSON configuration string for database connection

The DB_CONFIG format varies by database type. See the API documentation for database-specific configuration details.

Installation Methods

Option 1: Using UV (Recommended)

When using uv, no specific installation is needed. We will use uvx to directly run database-mcp.

UV Configuration Example:

REPLACE DB_TYPE and DB_CONFIG with your connection info.
{
    "mcpServers": {
      "database-mcp": {
        "command": "uvx",
        "args": [
          "database-mcp"
        ],
        "env": {
          "DB_TYPE": "pg",
          "DB_CONFIG": "{"host":"localhost","port":5432,"user":"user","password":"pw","dbname":"dbname"}"
        },
        "disabled": true,
        "autoApprove": []
      }
    }
}

Option 2: Using PIP

Install via pip:

pip install database-mcp

PIP Configuration Example:

{
  "mcpServers": {
    "database": {
      "command": "python",
      "args": [
        "-m", "database_mcp", 
        "--repository", "path/to/git/repo"
      ],
      "env": {
        "DB_TYPE": "pg",
        "DB_CONFIG": "{"host":"localhost","port":5432,"user":"user","password":"pw","dbname":"dbname"}"
      }
    }
  }
}

Running the Server

Development Mode

mcp dev mcp_server.py

Production Mode

python mcp_server.py

Configuration Methods

Environment Variables

export DB_TYPE="pg"  # or mysql, postgresql, etc.
export DB_CONFIG='{"host":"localhost","port":5432,"user":"username","password":"password","dbname":"database_name"}'
mcp dev mcp_server.py

Command Line Arguments

python mcp_server.py --db-type pg --db-config '{"host":"localhost","port":5432,"user":"username","password":"password","dbname":"database_name"}'

Or with UV:

uv mcp_server.py --db-type pg --db-config '{"host":"localhost","port":5432,"user":"username","password":"password","dbname":"database_name"}'

Exposed MCP Capabilities

Resources

Tools

Prompts

Development

Testing

uv pip install -e ".[dev]"
pytest

Publishing

rm -rf dist/ build/ *.egg-info/ && python -m build
python -m build
python -m twine upload dist/*

License

This repository is licensed under GPL