Multi Database MCP Server by FreePeak - MCP Server

Multi Database MCP Server

A powerful multi-database server implementing the Model Context Protocol (MCP) to provide AI assistants with structured access to databases.

Overview • Core Concepts • Features • Supported Databases • Deployment Options • Configuration • Available Tools • Examples • Troubleshooting • Contributing

Overview

The DB MCP Server provides a standardized way for AI models to interact with multiple databases simultaneously. Built on the FreePeak/cortex framework, it enables AI assistants to execute SQL queries, manage transactions, explore schemas, and analyze performance across different database systems through a unified interface.

Core Concepts

Multi-Database Support

Unlike traditional database connectors, DB MCP Server can connect to and interact with multiple databases concurrently:

{
  "connections": [
    {
      "id": "mysql1",
      "type": "mysql",
      "host": "localhost",
      "port": 3306,
      "name": "db1",
      "user": "user1",
      "password": "password1"
    },
    {
      "id": "postgres1",
      "type": "postgres",
      "host": "localhost",
      "port": 5432,
      "name": "db2",
      "user": "user2",
      "password": "password2"
    }
  ]
}

Dynamic Tool Generation

For each connected database, the server automatically generates specialized tools:

// For a database with ID "mysql1", these tools are generated:
query_mysql1       // Execute SQL queries
execute_mysql1     // Run data modification statements
transaction_mysql1 // Manage transactions
schema_mysql1      // Explore database schema
performance_mysql1 // Analyze query performance

Clean Architecture

The server follows Clean Architecture principles with these layers:

Domain Layer: Core business entities and interfaces
Repository Layer: Data access implementations
Use Case Layer: Application business logic
Delivery Layer: External interfaces (MCP tools)

Features

Simultaneous Multi-Database Support: Connect to multiple MySQL and PostgreSQL databases concurrently
Lazy Loading Mode: Defer connection establishment until first use - perfect for setups with 10+ databases (enable with --lazy-loading flag)
Database-Specific Tool Generation: Auto-creates specialized tools for each connected database
Clean Architecture: Modular design with clear separation of concerns
OpenAI Agents SDK Compatibility: Full compatibility for seamless AI assistant integration
Dynamic Database Tools: Execute queries, run statements, manage transactions, explore schemas, analyze performance
Unified Interface: Consistent interaction patterns across different database types
Connection Management: Simple configuration for multiple database connections
Health Check: Automatic validation of database connectivity on startup

Supported Databases

Database	Status	Features
MySQL	✅ Full Support	Queries, Transactions, Schema Analysis, Performance Insights
PostgreSQL	✅ Full Support (v9.6-17)	Queries, Transactions, Schema Analysis, Performance Insights
SQLite	✅ Full Support	File-based & In-memory databases, SQLCipher encryption support
TimescaleDB	✅ Full Support	Hypertables, Time-Series Queries, Continuous Aggregates, Compression, Retention Policies

Deployment Options

The DB MCP Server can be deployed in multiple ways to suit different environments and integration needs:

Docker Deployment

# Pull the latest image
docker pull freepeak/db-mcp-server:latest

# Run with mounted config file
docker run -p 9092:9092 \
  -v $(pwd)/config.json:/app/my-config.json \
  -e TRANSPORT_MODE=sse \
  -e CONFIG_PATH=/app/my-config.json \
  freepeak/db-mcp-server

Note: Mount to /app/my-config.json as the container has a default file at /app/config.json.

STDIO Mode (IDE Integration)

# Run the server in STDIO mode
./bin/server -t stdio -c config.json

For Cursor IDE integration, add to .cursor/mcp.json:

{
  "mcpServers": {
    "stdio-db-mcp-server": {
      "command": "/path/to/db-mcp-server/server",
      "args": ["-t", "stdio", "-c", "/path/to/config.json"]
    }
  }
}

SSE Mode (Server-Sent Events)

# Default configuration (localhost:9092)
./bin/server -t sse -c config.json

# Custom host and port
./bin/server -t sse -host 0.0.0.0 -port 8080 -c config.json

Client connection endpoint: http://localhost:9092/sse

Source Code Installation

# Clone the repository
git clone https://github.com/FreePeak/db-mcp-server.git
cd db-mcp-server

# Build the server
make build

# Run the server
./bin/server -t sse -c config.json

Configuration

Database Configuration File

Create a config.json file with your database connections:

{
  "connections": [
    {
      "id": "mysql1",
      "type": "mysql",
      "host": "mysql1",
      "port": 3306,
      "name": "db1",
      "user": "user1",
      "password": "password1",
      "query_timeout": 60,
      "max_open_conns": 20,
      "max_idle_conns": 5,
      "conn_max_lifetime_seconds": 300,
      "conn_max_idle_time_seconds": 60
    },
    {
      "id": "postgres1",
      "type": "postgres",
      "host": "postgres1",
      "port": 5432,
      "name": "db1",
      "user": "user1",
      "password": "password1"
    },
    {
      "id": "sqlite_app",
      "type": "sqlite",
      "database_path": "./data/app.db",
      "journal_mode": "WAL",
      "cache_size": 2000,
      "read_only": false,
      "use_modernc_driver": true,
      "query_timeout": 30,
      "max_open_conns": 1,
      "max_idle_conns": 1
    },
    {
      "id": "sqlite_encrypted",
      "type": "sqlite",
      "database_path": "./data/secure.db",
      "encryption_key": "your-secret-key-here",
      "journal_mode": "WAL",
      "use_modernc_driver": false
    },
    {
      "id": "sqlite_memory",
      "type": "sqlite",
      "database_path": ":memory:",
      "cache_size": 1000,
      "use_modernc_driver": true
    }
  ]
}

Command-Line Options

# Basic syntax
./bin/server -t <transport> -c <config-file>

# SSE transport options
./bin/server -t sse -host <hostname> -port <port> -c <config-file>

# Lazy loading mode (recommended for 10+ databases)
./bin/server -t stdio -c <config-file> --lazy-loading

# Customize log directory (useful for multi-project setups)
./bin/server -t stdio -c <config-file> -log-dir /tmp/db-mcp-logs

# Inline database configuration
./bin/server -t stdio -db-config '{"connections":[...]}'

# Environment variable configuration
export DB_CONFIG='{"connections":[...]}'
./bin/server -t stdio

Available Flags:

-t, -transport: Transport mode (stdio or sse)
-c, -config: Path to database configuration file
-p, -port: Server port for SSE mode (default: 9092)
-h, -host: Server host for SSE mode (default: localhost)
-log-level: Log level (debug, info, warn, error)
-log-dir: Directory for log files (default: ./logs in current directory)
-db-config: Inline JSON database configuration

SQLite Configuration Options

When using SQLite databases, you can leverage these additional configuration options:

SQLite Connection Parameters

Parameter	Type	Default	Description
`database_path`	string	Required	Path to SQLite database file or `:memory:` for in-memory
`encryption_key`	string	-	Key for SQLCipher encrypted databases
`read_only`	boolean	false	Open database in read-only mode
`cache_size`	integer	2000	SQLite cache size in pages
`journal_mode`	string	"WAL"	Journal mode: DELETE, TRUNCATE, PERSIST, WAL, OFF
`use_modernc_driver`	boolean	true	Use modernc.org/sqlite (CGO-free) or mattn/go-sqlite3

SQLite Examples

Basic File Database

{
  "id": "my_sqlite_db",
  "type": "sqlite",
  "database_path": "./data/myapp.db",
  "journal_mode": "WAL",
  "cache_size": 2000
}

Encrypted Database (SQLCipher)

{
  "id": "encrypted_db",
  "type": "sqlite",
  "database_path": "./data/secure.db",
  "encryption_key": "your-secret-encryption-key",
  "use_modernc_driver": false
}

In-Memory Database

{
  "id": "memory_db",
  "type": "sqlite",
  "database_path": ":memory:",
  "cache_size": 1000
}

Read-Only Database

{
  "id": "reference_data",
  "type": "sqlite",
  "database_path": "./data/reference.db",
  "read_only": true,
  "journal_mode": "DELETE"
}

Available Tools

For each connected database, DB MCP Server automatically generates these specialized tools:

Query Tools

Tool Name	Description
`query_<db_id>`	Execute SELECT queries and get results as a tabular dataset
`execute_<db_id>`	Run data manipulation statements (INSERT, UPDATE, DELETE)
`transaction_<db_id>`	Begin, commit, and rollback transactions

Schema Tools

Tool Name	Description
`schema_<db_id>`	Get information about tables, columns, indexes, and foreign keys
`generate_schema_<db_id>`	Generate SQL or code from database schema

Performance Tools

Tool Name	Description
`performance_<db_id>`	Analyze query performance and get optimization suggestions

TimescaleDB Tools

For PostgreSQL databases with TimescaleDB extension, these additional specialized tools are available:

Tool Name	Description
`timescaledb_<db_id>`	Perform general TimescaleDB operations
`create_hypertable_<db_id>`	Convert a standard table to a TimescaleDB hypertable
`list_hypertables_<db_id>`	List all hypertables in the database
`time_series_query_<db_id>`	Execute optimized time-series queries with bucketing
`time_series_analyze_<db_id>`	Analyze time-series data patterns
`continuous_aggregate_<db_id>`	Create materialized views that automatically update
`refresh_continuous_aggregate_<db_id>`	Manually refresh continuous aggregates

For detailed documentation on TimescaleDB tools, see .

Examples

Querying Multiple Databases

-- Query the MySQL database
query_mysql1("SELECT * FROM users LIMIT 10")

-- Query the PostgreSQL database in the same context
query_postgres1("SELECT * FROM products WHERE price > 100")

-- Query the SQLite database
query_sqlite_app("SELECT * FROM local_data WHERE created_at > datetime('now', '-1 day')")

Managing Transactions

-- Start a transaction
transaction_mysql1("BEGIN")

-- Execute statements within the transaction
execute_mysql1("INSERT INTO orders (customer_id, product_id) VALUES (1, 2)")
execute_mysql1("UPDATE inventory SET stock = stock - 1 WHERE product_id = 2")

-- Commit or rollback
transaction_mysql1("COMMIT")
-- OR
transaction_mysql1("ROLLBACK")

Exploring Database Schema

-- Get all tables in the database
schema_mysql1("tables")

-- Get columns for a specific table
schema_mysql1("columns", "users")

-- Get constraints
schema_mysql1("constraints", "orders")

Working with SQLite-Specific Features

-- Create a table in SQLite
execute_sqlite_app("CREATE TABLE IF NOT EXISTS local_cache (key TEXT PRIMARY KEY, value TEXT, timestamp DATETIME)")

-- Use SQLite-specific date functions
query_sqlite_app("SELECT * FROM events WHERE date(created_at) = date('now')")

-- Query SQLite master table for schema information
query_sqlite_app("SELECT name, sql FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'")

-- Performance optimization with WAL mode
execute_sqlite_app("PRAGMA journal_mode = WAL")
execute_sqlite_app("PRAGMA synchronous = NORMAL")

Troubleshooting

Common Issues

Connection Failures: Verify network connectivity and database credentials
Permission Errors: Ensure the database user has appropriate permissions
Timeout Issues: Check the query_timeout setting in your configuration

Logs

Enable verbose logging for troubleshooting:

./bin/server -t sse -c config.json -v

Contributing

We welcome contributions to the DB MCP Server project! To contribute:

Fork the repository
Create a feature branch (git checkout -b feature/amazing-feature)
Commit your changes (git commit -m 'feat: add amazing feature')
Push to the branch (git push origin feature/amazing-feature)
Open a Pull Request

Please see our file for detailed guidelines.

License

This project is licensed under the MIT License - see the file for details.

FreePeak/db-mcp-server