Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add vinnie357/claude-skills/plugin install agent-sandboxingWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/vinnie357/claude-skills/sandbox)<a href="https://agentmods.dev/skills/vinnie357/claude-skills/sandbox"><img src="https://agentmods.dev/badge/skills/vinnie357/claude-skills/sandbox/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/vinnie357/claude-skills/sandbox"><img src="https://agentmods.dev/badge/skills/vinnie357/claude-skills/sandbox.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00088 | $0.02010 |
| Opus 5 | $0.00044 | $0.01005 |
| Sonnet 5 | $0.00018 | $0.00402 |
| Haiku 4.5 | $0.00009 | $0.00201 |
Grade A, and why
sandbox scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.
sandbox
Entry-point index for the agent-sandboxing plugin. Load this skill first when the task is "give me an isolated environment for an AI agent" and you don't yet know which substrate fits. The body routes to the right deeper skill via decision tree + one-line index.
The plugin covers the Kubernetes-orchestrated path (multi-pod, per-session lifecycle, controller-managed). For the single-host CLI path (one operator, one machine, Docker microVMs), the sibling sbx plugin is the right tool — same mental goal, different shape.
Decision tree
Need to sandbox an AI agent
│
├─ Single host, macOS, TRUSTED workload needing a Linux dev environment?
│ └─→ /core:container (container machine, 1.0.0+ — host home mounted; NOT agent isolation)
│
├─ Single host, no Kubernetes?
│ └─→ /sbx:sbx (Docker microVMs, sbx CLI)
│
└─ Kubernetes (kind / GKE / kina)?
│
├─ Host OS = macOS Apple Silicon?
│ └─→ /agent-sandboxing:kina-microvm (Apple Container microVM nodes)
│
├─ Host OS = Linux + want microVM isolation?
│ └─→ /agent-sandboxing:kata-on-kind (Kata Containers on kind)
│
├─ Production GKE + microVM isolation?
│ └─→ /agent-sandboxing:kata-on-gke (self-managed Kata on Ubuntu N2)
│
└─ Production GKE + userspace kernel isolation?
└─→ /agent-sandboxing:k8s-agent-sandbox (covers GKE managed Agent Sandbox = gVisor)
For every k8s path: also load /agent-sandboxing:k8s-agent-sandbox (controller + CRDs + lifecycle) and /agent-sandboxing:claude-code-on-sandbox (workload packaging).
Isolation tier comparison
| Tier | Mechanism | Where it runs | Plugin skill |
|---|---|---|---|
| Hardware microVM (KVM) | Kata Containers | Linux + nested virt | kata-on-kind, kata-on-gke |
| Hardware microVM (Virtualization.framework) | Apple Container, node-level | macOS Apple Silicon | kina-microvm |
| Hardware microVM (KVM/Docker) | sbx CLI, single-host | Linux + macOS | /sbx:sbx (sibling plugin) |
| Hardware microVM, host-integrated | Apple Container machine (1.0.0+) |
macOS Apple Silicon | /core:container — dev convenience tier, NOT isolation (host home mounted) |
| Userspace kernel | gVisor | Anywhere (no nested virt needed) | k8s-agent-sandbox (gVisor variant) |
| Process-level (none) | runc default | Anywhere | Not recommended for untrusted agents |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 7d ago First seen · 99 lines · 88 tokens per session scan A 4ee7a7f4279e
sandbox is a skill published in the GitHub repository vinnie357/claude-skills (25 stars, last pushed today), licensed MIT. It adds 88 tokens to every session and 2,010 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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