Query PostgreSQL Databases with Claude

The PostgreSQL MCP server gives Claude read-only access to PostgreSQL databases for data analysis and schema inspection. It exposes three tools: query (executes a read-only SQL query, restricted to SELECT statements for safety), list_tables (lists all tables in the database), and describe_table (returns column and schema information for a named table). It also exposes the database schema as resources - a full-schema resource and a per-table schema resource - so Claude can inspect structure without running a query first.

Use it when you need Claude to analyze data or inspect schema in an existing PostgreSQL database without risk of writing to it. It is not for write operations: only SELECT queries are permitted, and the security guidance recommends connecting through a read-replica in production and limiting accessible schemas rather than granting broad access.

Given a natural-language request, Claude inspects the relevant table schema, writes an appropriate SQL query, executes it through the query tool, and presents the results - for example, analyzing a users table to show signup distribution by month. The list_tables and describe_table tools let Claude discover database structure on its own before writing a query, rather than requiring the schema to be provided up front. The server also exposes the schema directly as resources - postgres://schema for the full database schema and postgres://tables/{table_name} for an individual table's schema - so Claude can pull structure without invoking a tool call.

Install globally via npm install -g @modelcontextprotocol/server-postgres, then add the server to your Claude Code MCP configuration with the connection string as an argument to npx.

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-postgres",
        "postgresql://user:password@localhost:5432/database"
      ]
    }
  }
}

Use a connection string with appropriately scoped credentials - read-only access is the default behavior.

Developers and analysts who want Claude to explore and query a PostgreSQL database directly - inspecting schema, running ad hoc SELECT queries, and summarizing results - without any risk of the connector writing to the database.