Biscuit includes Tor: there’s nothing to install. Turn on Tor mode at first launch, or later in Settings › Network › Proxy, and Biscuit hides your IP address from the nodes, servers and swap partners it talks to.
The onion at the bottom right of the window shows the mode: purple in Tor mode, grey for a direct connection. Click it to change. Exchange swaps are off in Tor mode (see why); atomic swaps work.
The Node traffic setting decides how Biscuit reaches Monero nodes in Tor mode:
Before Biscuit 1.0.10, the default was Switch to Tor after initial synchronization, and every wallet synced outside Tor each time it was opened. Biscuit 1.0.10 moves anyone who had that setting to Always over Tor, once; you can choose it again in Settings › Network › Proxy. A node on your own network is always reached directly, whatever the setting.
Only allow connections to onion services keeps every connection inside the Tor network: Monero uses .onion nodes only, and prices come from our onion. Bitcoin and Litecoin stay offline unless you set your own Electrum server with an .onion address: no public onion Electrum server is built in yet.
Show status shows Tor’s log, handy if it doesn’t connect.
In Tor mode, Biscuit asks biscuitwallet.com from time to time whether its connection arrives through Tor. The answer is only yes or no, and nothing is kept. If the answer is no (a wrong proxy setting, or a program on 127.0.0.1:9050 that isn’t Tor), the status bar shows Not going through Tor. Click it to open the proxy settings. The check is off when third-party data is disabled.