Glossary
Sandbox
A bounded machine, often a virtual machine or container, where an agent's actions run so a mistake stays inside it.
A sandbox is a bounded machine where an agent's actions run. A virtual machine or a container is the usual form. The point is containment: a bad click, a bad command, or a hostile page stays inside that machine.
The harness decides which commands are even offered. A guardrail can still pause a step inside the sandbox. Computer use is one reason the boundary matters, because the model is asking for real pointer and keyboard actions.
Anthropic's computer-use page lists a dedicated virtual machine or container with minimal privileges as a precaution. OpenAI's computer-use guide says to use an isolated browser or virtual machine. Google's Computer Use guide says to run the agent in a sandboxed virtual machine or container, separate from the host. The longer guide is Can an AI agent use your computer?.