Your key stays in this browser (saved to local storage) and is sent straight to Anthropic. That's fine for personal and local use. For a public site, put a proxy URL below so the key never ships to visitors.
Point this at your own proxy (e.g. a Cloudflare Worker) to keep the key server-side. Leave as the default to call Anthropic directly with the key above.
Let the assistant look up current docs and cite sources.