SQL MCP Server Demo

This repository implements a local Model Context Protocol (MCP) server for SQL Server using Microsoft Data API Builder (DAB) 2.0. It exposes read-only data access tools (describe_entities, read_records, and aggregate_records) to a local Ollama model (qwen3:8b) via a Python MCP client.

Repository Structure

A:\sql-mcp-demo
│   .env                 - Environment variables configuration
│   README.md            - Project documentation
│   requirements.txt     - Python dependencies
│   test_ollama.py       - Verifies basic connection to Ollama
│   test_tools.py        - Verifies tool-calling capability of qwen3:8b
│
├── .venv/               - Python virtual environment
│
├── dab/
│   └── dab-config.json  - Schema-valid Data API Builder configuration
│
└── database/
    └── verify.sql       - Reference database queries

Related MCP server: Python MSSQL MCP Server

Architecture

           ┌──────────────────────┐
           │      Qwen3:8B        │
           │       Ollama         │
           └──────────┬───────────┘
                      │
                      │ Tool Calling
                      ▼
           ┌──────────────────────┐
           │    MCP Client        │
           │     Python           │
           └──────────┬───────────┘
                      │
                      │ MCP HTTP
                      ▼
           ┌──────────────────────┐
           │ Data API Builder     │
           │    SQL MCP Server    │
           │ localhost:5000/mcp   │
           └──────────┬───────────┘
                      │
                      │
                      ▼
           ┌──────────────────────┐
           │ SQL Server LocalDB   │
           │                      │
           │ EmployeeDB           │
           │ └── dbo.Employee     │
           └──────────────────────┘

Running the Project

1. Verify Services: Ensure SQL Server LocalDB and Ollama are started:

   sqllocaldb start MSSQLLocalDB
   ollama run qwen3:8b

2. Start the Data API Builder MCP Server: From a:\sql-mcp-demo:

   dab start --config .\dab\dab-config.json

   The MCP endpoint is exposed at http://localhost:5000/mcp.

3. Verify via MCP Inspector: Launch the Inspector in proxy mode:

   npx -y @modelcontextprotocol/inspector http://localhost:5000/mcp

   Open the printed URL in your browser to verify that the describe_entities, read_records, and aggregate_records tools are active.

4. Run Python Client Verification: Ensure your virtual environment is active:

   .venv\Scripts\activate

   Verify Ollama connection:

   python test_ollama.py

   Verify tool calling:

   python test_tools.py

Schema Validation Bug Fixed

A critical schema validation issue in Microsoft's Data API Builder v2.0.9 was addressed:

• The standard DAB schema validator contains a bug where defining "mcp" at the entity level for table types incorrectly triggers a stored-procedure constraint (requiring source.type to be stored-procedure).

• This was resolved by removing the redundant entity-level "mcp" block since MCP capability is already configured globally at the runtime level.