PostgreSQL

PostgreSQL is the open-source relational database that powers critical data for thousands of products. The official MCP server provides "read-only access to PostgreSQL databases" so Claude can inspect schemas and run read queries without opening a separate SQL tool.

What it does: it exposes a query tool to execute read-only SQL against the connected database and schema resources for each table. The official README states that "All queries are executed within a READ ONLY transaction", making it useful for analysis, support, debugging and data exploration.

What you can ask

• "List the tables available in this database and explain the likely relationships."
• "Run a SELECT that counts active customers by plan for the last 30 days."
• "Inspect the schema for the orders table and suggest the safest query for revenue by month."

What connection you need

You need a Postgres connection URL for a specific database, for example postgresql://user:password@host:5432/db. The official README shows the connection argument in args and says: "Replace /mydb with your database name."

1. Create a dedicated Postgres user for Terminal Sync.
2. Give it the minimum read permissions for the tables it needs.
3. Paste the connection URL when the Lab asks for POSTGRES_URL. Terminal Sync stores it encrypted in your Keychain.

Even though the server executes queries in a READ ONLY transaction, we also recommend using a read-only database role for defense in depth.