Read Only Local Postgres MCP Server

PostgreSQL MCP Server

A Model Context Protocol (MCP) server that enables Claude Desktop to interact with PostgreSQL databases through natural language queries.

Features

• Execute read-only SQL queries through Claude Desktop or Claude Code
• Dynamic database connections - connect to any PostgreSQL database at runtime
• Built-in security: statement validation plus database-enforced READ ONLY transactions
• Easy integration with Claude Desktop and Claude Code
• JSON formatted query results
• Environment-based default configuration with runtime override support

Quick Start

For Claude Code Users (Recommended - Easiest Method)

claude mcp add postgres -s user -- npx -y @hovecapital/read-only-postgres-mcp-server

Then set your database environment variables:

export DB_HOST=localhost

export DB_PORT=5432 export DB_DATABASE=your_database_name export DB_USERNAME=your_username export DB_PASSWORD=your_password

Done! Restart Claude Code and ask: "What tables are in my database?"

For Claude Desktop Users (Manual Configuration)

1. Open your config file:

# macOS

open ~/Library/Application\ Support/Claude/claude_desktop_config.json

Windows

notepad %APPDATA%\Claude\claude_desktop_config.json

2. Add this configuration:

{

"mcpServers": { "postgres": { "command": "npx", "args": ["-y", "@hovecapital/read-only-postgres-mcp-server"], "env": { "DB_HOST": "localhost", "DB_PORT": "5432", "DB_DATABASE": "your_database_name", "DB_USERNAME": "your_username", "DB_PASSWORD": "your_password" } } } }

3. Save, restart Claude Desktop, and test!

Prerequisites

• Node.js (v16 or higher) - If using mise, update the command path accordingly
• PostgreSQL database server
• Claude Desktop application

Installation

Option 1: Install from MCP Registry (Recommended)

This server is published in the Model Context Protocol Registry as capital.hove/read-only-local-postgres-mcp-server.

Method A: Claude Code CLI (Easiest!)

claude mcp add postgres -s user -- npx -y @hovecapital/read-only-postgres-mcp-server

Then configure your database credentials using environment variables. Restart Claude Code and you're done!

Benefits:

• One command installation
• No manual JSON editing
• Automatic configuration

Method B: Manual JSON Configuration

For Claude Desktop:

Edit ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{

"mcpServers": { "postgres": { "command": "npx", "args": ["-y", "@hovecapital/read-only-postgres-mcp-server"], "env": { "DB_HOST": "localhost", "DB_PORT": "5432", "DB_DATABASE": "your_database_name", "DB_USERNAME": "your_username", "DB_PASSWORD": "your_password" } } } }

For Claude Code:

Edit ~/.config/claude-code/settings.json (macOS/Linux) or %APPDATA%\claude-code\settings.json (Windows):

{

"mcp": { "servers": { "postgres": { "command": "npx", "args": ["-y", "@hovecapital/read-only-postgres-mcp-server"], "env": { "DB_HOST": "localhost", "DB_PORT": "5432", "DB_DATABASE": "your_database_name", "DB_USERNAME": "your_username", "DB_PASSWORD": "your_password" } } } } }

Option 2: Install from npm

npm install -g @hovecapital/read-only-postgres-mcp-server

Option 3: Installation with Claude Code

If you're using Claude Code, you can easily install this MCP server:

# Clone the repository

git clone https://github.com/hovecapital/read-only-local-postgres-mcp-server.git cd read-only-local-postgres-mcp-server

Install dependencies and build

npm install npm run build

Then configure Claude Code by adding to your MCP settings.

Option 4: Manual Installation

1. Clone or Download

Save the repository to a directory on your system:

mkdir ~/mcp-servers/postgres

cd ~/mcp-servers/postgres git clone https://github.com/hovecapital/read-only-local-postgres-mcp-server.git .

2. Install Dependencies

npm install

npm run build

Configuration

Note: If you installed via Option 1 (MCP Registry with npx), you've already configured everything! This section is for users who chose Options 2, 3, or 4 (npm or manual installation).

Claude Code Configuration

If you're using Claude Code with a manual installation, add the PostgreSQL server to your MCP settings:

1. Open your Claude Code settings (typically in ~/.config/claude-code/settings.json on macOS/Linux or %APPDATA%\claude-code\settings.json on Windows)

1. Add the PostgreSQL MCP server configuration:

{

"mcp": { "servers": { "postgres": { "command": "node", "args": ["/absolute/path/to/read-only-local-postgres-mcp-server/dist/index.js"], "env": { "DB_HOST": "localhost", "DB_PORT": "5432", "DB_DATABASE": "your_database_name", "DB_USERNAME": "your_username", "DB_PASSWORD": "your_password" } } } } }

1. Restart Claude Code for the changes to take effect.

Claude Desktop Configuration

If you're using Claude Desktop with a manual installation, open your Claude Desktop configuration file:

macOS:

~/Library/Application Support/Claude/claude_desktop_config.json

Windows:

%APPDATA%\Claude\claude_desktop_config.json

Add the PostgreSQL server configuration:

{

"mcpServers": { "postgres": { "command": "node", "args": ["/absolute/path/to/read-only-local-postgres-mcp-server/dist/index.js"], "env": { "DB_HOST": "localhost", "DB_PORT": "5432", "DB_DATABASE": "your_database_name", "DB_USERNAME": "your_username", "DB_PASSWORD": "your_password" } } } }

Using mise for Node.js

If you're using mise for Node.js version management, make sure to use the full path to the Node.js executable in your configuration.

Environment Variables

Tools

This MCP server exposes three tools that Claude can use to interact with PostgreSQL databases.

connect

Connect to a PostgreSQL database using a connection string. The connection persists for subsequent queries until changed or disconnected. The target must be DB_HOST:DB_PORT or listed in DB_ALLOWED_HOSTS.

Parameters:

Connection String Format:

postgres://username:password@host:port/database?sslmode=require

postgresql://username:password@host:port/database

SSL Modes Supported:

• sslmode=require - Require SSL (recommended for remote connections)
• sslmode=verify-full - Require SSL with certificate verification
• No sslmode parameter - No SSL (for local connections)

Example Usage (natural language):

"Connect to postgres://myuser:mypass@db.example.com:5432/production"

"Connect to this database: postgres://admin:secret@localhost/analytics"

Response:

{

"status": "connected", "host": "db.example.com", "port": 5432, "database": "production", "user": "myuser", "ssl": true }

---

disconnect

Disconnect from the current runtime database and revert to the default environment-configured connection.

Parameters: None

Example Usage (natural language):

"Disconnect from the current database"

"Go back to the default database"

Response:

{

"status": "disconnected", "message": "Reverted to default environment connection", "host": "localhost", "database": "postgres" }

---

query

Run a read-only SQL query against the currently connected database. Optionally override the connection for a single query.

Parameters:

Example Usage (natural language):

"Show me all tables in the database"

"SELECT * FROM users LIMIT 10" "Run this query on postgres://other:pass@host/db: SELECT count(*) FROM orders"

Response:

[

{ "id": 1, "name": "Alice", "email": "alice@example.com" }, { "id": 2, "name": "Bob", "email": "bob@example.com" } ]

---

Tool Reference for LLMs

When using this MCP server, Claude can:

1. Query the default database (configured via environment variables):

   User: "What tables are in my database?"

Claude: [Uses query tool with SQL: "SELECT table_name FROM information_schema.tables WHERE table_schema = 'public'"]

1. Connect to a different database dynamically:

   User: "Connect to postgres://user:pass@newhost/newdb and show me the users table"

Claude: [Uses connect tool first, then query tool]

1. One-off query to a different database (without switching active connection):

   User: "How many records are in the orders table on postgres://user:pass@analytics/warehouse?"

Claude: [Uses query tool with connectionString parameter]

1. Revert to default connection:

   User: "Go back to my local database"

Claude: [Uses disconnect tool]

Usage

1. Restart Claude Desktop/Code after updating the configuration
2. Start chatting with Claude about your database

Example Queries

Basic queries (uses default/active connection):

"Show me all tables in my database"

"What's the structure of the users table?" "Get the first 10 records from the products table" "How many orders were placed last month?" "Show me users with email addresses ending in @gmail.com"

Dynamic connection examples:

"Connect to postgres://analyst:password@analytics.example.com:5432/warehouse"

"Now show me all the tables" "What's the total revenue in the sales table?" "Disconnect and go back to my local database"

One-off queries to different databases:

"Run SELECT count(*) FROM users on postgres://admin:secret@prod.example.com/app"

"Check the orders table on my staging database: postgres://dev:dev@staging/app"

Claude will automatically convert your natural language requests into appropriate SQL queries and execute them against your database.

Security Features

Read-Only Operations

The server enforces read-only access on all connections (both environment-configured and runtime dynamic connections) in three layers:

1. Database-enforced read-only transaction. Every query runs inside BEGIN READ ONLY, and the connection is closed afterwards, so nothing is ever committed. PostgreSQL itself rejects INSERT, UPDATE, DELETE, MERGE, DDL, SELECT INTO, nextval(), large-object writes and any writ