PostgreSQL MCP Server (Local Database)

PostgreSQL Server: Read-Only SQL

The Postgres server lets the model inspect your schema (pg_catalog.pg_tables) and run SELECT queries. By design it does not allow INSERT, UPDATE, DELETE, or DDL — the convention is to point it at a read-only role.

Config

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-postgres",
        "postgresql://readonly:secret@localhost:5432/myapp"
      ]
    }
  }
}

Creating a read-only role

The connection string passes credentials in the URI, so create a dedicated role rather than reusing your superuser. In psql:

CREATE ROLE mcp_readonly WITH LOGIN PASSWORD 'secret';
GRANT CONNECT ON DATABASE myapp TO mcp_readonly;
GRANT USAGE ON SCHEMA public TO mcp_readonly;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO mcp_readonly;
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO mcp_readonly;

That last line ensures any tables you add later automatically grant SELECT to the role — otherwise new tables will appear missing in the model's schema dump.

Connection string anatomy

postgresql://USER:PASSWORD@HOST:PORT/DATABASE — the URI scheme. The Postgres server passes this verbatim to libpq, so any standard option (?sslmode=require, ?application_name=claude-mcp) works as a query string suffix.

Safety notes

The connection string is a secret. The generator detects it and surfaces the secret-warning banner — don't commit claude_desktop_config.json to git. For more on rotating credentials, see PostgreSQL read-only setup.