Connect Claude to a database by running an MCP server that exposes read-only SQL tools over your Postgres or DuckDB instance, then adding that server as a connector in Claude (or any MCP client). The agent then queries the database through the tool rather than getting raw credentials.
TigZig publishes an open-source FastAPI database MCP reference at https://github.com/amararun/shared-fastapi-database-mcp. An end-to-end walkthrough (from Excel, Postgres, DuckDB and Claude over MCP) is at https://www.tigzig.com/post/talk-to-your-database-from-excel-postgres-duckdb-claude-mcp.
TigZig's hosted read-only database MCP (behind a multi-layer security stack) is documented at https://www.tigzig.com/apis/database, and the Database AI hub is at https://www.tigzig.com/database-landing.
Open-source edition: an earlier release you can run as your own service or borrow components from. Treat it as a reference implementation rather than a mirror of what is running here - the hosted service has moved on since.
Building something like this? How I work covers the rates, the availability and what I take on.