Agent Sandboxing
Agent sandboxing isolates the environment in which an agent executes code or tools, limiting the resources and external systems it can affect. The practitioner configures filesystem, network, process and credential boundaries so untrusted actions have a contained execution scope and can be stopped or discarded.
What it is
A sandbox creates a restricted execution context using mechanisms such as containers, virtual machines, microVMs or system-call interception. These mechanisms differ in isolation strength, compatibility and startup cost. An agent sandbox may additionally restrict network destinations, mount selected files and inject only task-specific credentials. Its purpose is to enforce boundaries even when generated code or an external instruction is incorrect. This differs from output guardrails, which inspect content or proposed actions. Isolation controls what execution can reach; policy determines what it should be allowed to do. Both are needed when an agent can perform effects beyond producing text.
What the work involves
The practitioner identifies the assets exposed to execution, chooses an isolation mechanism and tests its actual restrictions. Limits on CPU, memory, disk and runtime contain resource abuse. Writable mounts and network access should match the task, and credentials should have narrow scope and short lifetimes where possible. Useful artifacts include an environment specification and containment tests for disallowed files, destinations and processes. Cleanup rules remove temporary state while preserving explicitly requested outputs and the logs needed to inspect a run.
Illustrative example
An analysis agent runs a script supplied through a document-processing task. The sandbox provides the uploaded files and a temporary output directory but no production database credentials. Outbound network access is disabled because the task needs only local computation. Tests attempt to read an unrelated host file, spawn excessive processes and write beyond the mount. The valid output is exported after inspection, while the environment is destroyed at the end of the run.
Limits and common mistakes
A container configuration alone does not establish strong isolation from every host vulnerability. Permitted credentials or network paths can still allow harmful actions inside the authorized boundary. Sandbox escapes, shared-resource leaks and configuration errors require attention to the chosen mechanism's threat model. Quality means verified restrictions and controlled artifact export, not simply calling an environment a sandbox. Isolation also does not make generated results trustworthy; task correctness needs separate validation after contained execution.
Prerequisites
Sandboxing exists to contain code-executing agents.
- mediumDocker
Containers are the baseline isolation primitive.
Sources and further reading
- What is gVisor?
Explains application-kernel isolation, its security purpose and compatibility tradeoffs relative to ordinary containers.
Last updated: 2026-10-10