Sandboxing confines Bash tool execution to an allowlist of paths and hosts. It's how you let Claude run commands without granting the shell full reach into your machine.

What it does

On Linux and macOS, Claude Code can launch Bash calls inside a sandbox that restricts filesystem access to the project directory and network access to a configured allowlist. Commands that try to reach outside the allowed area fail fast with a clear error. This is the strongest containment option short of a full container.

When to use it

Granting broad Bash access without worrying about rogue commands.
Running untrusted or generated scripts safely.
Multi-tenant environments where you can't trust every skill or prompt.
Any setup where you want defense-in-depth on top of permission rules.

Gotchas

Some tools need network access you might not have whitelisted. Watch for "blocked by sandbox" errors and allowlist specifically.
Sandboxing has performance overhead - small for most work, noticeable for file-heavy tasks.
Not available on Windows. Use WSL2 or a container instead.

Official docs: https://code.claude.com/docs/en/sandboxing.md