generate-sandbox-policy

A skill for turning plain-language access requirements and API documentation into YAML sandbox network policies. These policies control which network connections and API endpoints an agent may use.

In plain words
What is it for?
Use it to define host, port, endpoint, access-level, middleware, and failure-behavior rules for an agent's API access.
Why use it?
It reduces the effort and mistakes involved in translating access rules into correctly structured security configuration.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/nvidia/openshell/generate-sandbox-policy
Any agent
npx skills add NVIDIA/OpenShell --skill generate-sandbox-policy
Clone the repo
git clone --depth 1 https://github.com/NVIDIA/OpenShell

Made for: Claude Code, Codex.

Per session 98 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 7,891 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00098 $0.07891
Opus 5 $0.00049 $0.03946
Sonnet 5 $0.00020 $0.01578
Haiku 4.5 $0.00010 $0.00789

Measured 2d ago against content hash af89ee43e5db, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

generate-sandbox-policy scanned grade A with 1 finding 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 2d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- "Allow curl to hit api.github.com, read-only"
.agents/skills/generate-sandbox-policy/SKILL.md · 652 lines

How it starts

The opening of the file, as written. The whole thing — 652 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Generate Sandbox Policy

Generate YAML sandbox network policies and network middleware configuration from API documentation and natural-language user requirements.

Overview

This skill translates a user's plain-language policy intent into a valid sandbox policy. The amount of detail the user provides determines the granularity of the generated policy — from broad L4 or preset-based policies (just a host:port) up to fine-grained per-endpoint L7 rules (full API docs).

The output is a network_policies YAML block, an optional network_middlewares block, and optionally a full policy file that conforms to the sandbox policy schema.

Step 1: Gather Inputs

Determine the Detail Tier

The user's input falls into one of three tiers. Work with whatever the user provides — do not require a higher tier than needed.

Tier User provides What you can generate
Minimal Host(s) and plain-language intent L4-only policies, or L7 with access presets (read-only, read-write, full)
Moderate Host(s) + some known URL paths or resources L7 with targeted glob rules for known paths, presets for the rest
Full Complete API docs (OpenAPI, Swagger, markdown, URL) Fine-grained per-endpoint L7 rules with specific method+path combinations

Minimal Tier (host + intent only)

The user provides API endpoints and a broad intent. No API docs needed.

Examples:

  • "Allow curl to hit api.github.com, read-only"
  • "Give claude full access to api.anthropic.com"
  • "Let /usr/bin/myapp talk to internal-svc:8080 but only for reading"

This is sufficient for:

  • L4-only policies (allow all traffic to host:port, no HTTP inspection)
  • Preset-based L7 policies (read-only, read-write, full on all paths)

For this tier, default to:

  • access: read-only when the user says "read", "browse", "view", "query", "fetch"
  • access: read-write when the user says "read-write", "create", "update" (but not "delete")
  • access: full when the user says "full access", "everything", "unrestricted"
  • L4-only when the user says "just allow it", "pass through", or "no inspection". Omit protocol for explicit-proxy clients. Use protocol: tcp only when the workload must use native DNS and direct socket calls, the endpoint has a valid DNS hostname, and the selected runtime support (currently Docker and Podman).

Read the full file on GitHub · 652 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

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.

  1. 2d ago First seen · 652 lines · 98 tokens per session scan A af89ee43e5db

Subscribe to this mod's changes

generate-sandbox-policy is a skill published in the GitHub repository NVIDIA/OpenShell (8,475 stars, last pushed today), licensed Apache-2.0. It adds 98 tokens to every session and 7,891 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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