MCP Dummy DB Integration MCP Server

MCP Agent POC

This project demonstrates a secure, production-ready implementation of the Model Context Protocol (MCP) as a connector layer between AI agents and PostgreSQL databases. The solution enables natural language queries without exposing database credentials to the LLM.

Key Achievement: LLM cannot access database directly - only through predefined MCP tools.

🏗️ Architecture Overview

┌────────────────────────────────────────────────────────┐
│                    USER QUERY                         │
│          "Fetch employees in AI department"           │
└───────────────────┬────────────────────────────────────┘
                    │
                    ▼
┌────────────────────────────────────────────────────────┐
│         PLANNER AGENT (LLM)                           │
│  ✓ Natural Language Understanding                     │
│  ✗ NO database credentials                            │
│  Output: {"tool": "get_employees_by_department",      │
│           "parameters": {"department": "AI"}}         │
└───────────────────┬────────────────────────────────────┘
                    │
                    ▼
┌────────────────────────────────────────────────────────┐
│         EXECUTOR AGENT                                 │
│  ✓ Validates tool request                            │
│  ✓ Maps to allowed operations only                   │
│  ✗ Cannot execute arbitrary SQL                      │
└───────────────────┬────────────────────────────────────┘
                    │
                    ▼
┌────────────────────────────────────────────────────────┐
│         MCP TOOLS LAYER (Sandbox)                     │
│  ✓ get_employees_by_department("AI")                │
│  ✓ get_projects_by_status("Completed")              │
│  ✓ get_issues_by_priority("High")                   │
│  ✗ Cannot run arbitrary SQL                          │
└───────────────────┬────────────────────────────────────┘
                    │
                    ▼
┌────────────────────────────────────────────────────────┐
│         DATABASE CONNECTION (Secure)                  │
│  ✓ Credentials in environment variables             │
│  ✓ Only parameterized queries (SQL injection safe)  │
└───────────────────┬────────────────────────────────────┘
                    │
                    ▼
┌────────────────────────────────────────────────────────┐
│         RESULT TO USER                               │
│    [Secure data retrieval via MCP]                   │
└────────────────────────────────────────────────────────┘

🔒 Security Features

Project Structure

• app/agents/: The brain (Planner, Executor, Orchestrator)
• app/mcp/: The tool layer (Connector to DB)
• app/database/: Low-level DB connection pool
• app/api/: FastAPI routes

Getting Started

1. Setup Env

Copy the example config:

cp .env.example .env

2. Run with Docker

The easiest way to stand it up (Postgres + API):

docker-compose up --build

The API listens on http://localhost:8000.

3. Test It

You can use the swagger UI at /docs or curl:

curl -X POST "http://localhost:8000/api/v1/query" \
     -H "Content-Type: application/json" \
     -d '{"query": "Find all projects that are in progress"}'

Local Dev (No Docker)

If you have Python 3.11+ and a local Postgres running:

1. pip install -r requirements.txt
2. Update .env with your DB credentials
3. python -m app.main