agents-at-scale-ark: Skill for Claude Code

.claude/skills/ark-setup-cluster/SKILL.md

ark-setup-cluster is a skill for Claude Code from mckinsey/agents-at-scale-ark. It costs 54 tokens per session (1,093 once invoked), scanned C, original, Apache-2.0.

A setup workflow for installing the Ark platform in Kubernetes, a system for running applications in managed containers, using an existing or separate local cluster.

In plain words
What is it for?
It is for installing, configuring, troubleshooting, and preparing Ark environments for end-to-end testing.
Why use it?
It helps deploy Ark safely while checking the current cluster first and avoiding accidental changes to existing work.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is mckinsey/agents-at-scale-ark's own configuration. It tells Claude Code how to work on agents-at-scale-ark itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything agents-at-scale-ark configures →

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is node tools/ark-cli/dist/index.js install --yes --wait-for-ready 5m.

Reuse

Borrowing it

Nothing to install: this file belongs to mckinsey/agents-at-scale-ark. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/mckinsey/agents-at-scale-ark/main/.claude/skills/ark-setup-cluster/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/mckinsey/agents-at-scale-ark

Made for: Claude Code.

Wrote 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.

agentmods badge for ark-setup-cluster

README.md
[![agentmods](https://agentmods.dev/badge/skills/mckinsey/agents-at-scale-ark/ark-setup-cluster/github.svg)](https://agentmods.dev/skills/mckinsey/agents-at-scale-ark/ark-setup-cluster)
Your own site
<a href="https://agentmods.dev/skills/mckinsey/agents-at-scale-ark/ark-setup-cluster"><img src="https://agentmods.dev/badge/skills/mckinsey/agents-at-scale-ark/ark-setup-cluster/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.

agentmods 80×15 button for ark-setup-cluster

Your own site · 80×15
<a href="https://agentmods.dev/skills/mckinsey/agents-at-scale-ark/ark-setup-cluster"><img src="https://agentmods.dev/badge/skills/mckinsey/agents-at-scale-ark/ark-setup-cluster.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,093 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 4 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Privilege Escalation · line 63
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 67
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 71
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 67
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
How audits are shown
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 5.1 $0.00054 $0.01093
Opus 5 $0.00027 $0.00547
Sonnet 5 $0.00011 $0.00219
Haiku 4.5 $0.00005 $0.00109

Measured 9d ago against content hash d4769315d870, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade C, and why

ark-setup-cluster scanned grade C 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 9d 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.

Reaches for credential fileshighPrivilege escalation

SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.

kind get kubeconfig --name <cluster-name> --internal | sed "s/<cluster-name>-control-plane/$CONTROL_PLANE_IP/g" > ~/.kube/config
.claude/skills/ark-setup-cluster/SKILL.md · 143 lines

How it starts

The opening of the file, as written. The whole thing — 143 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ark Setup Cluster

Set up and install the Ark platform using ark-cli. Supports two modes:

  • Default: Deploy Ark to an existing cluster
  • Isolated e2e: Create a dedicated Kind cluster for testing without affecting existing clusters

When to use this skill

  • User wants to install or set up Ark
  • Build manager needs an isolated cluster for e2e testing
  • User needs to deploy Ark to their local cluster
  • User needs to troubleshoot Ark installation issues

Prerequisites

  1. Docker - Required for Kind cluster creation
  2. kubectl - Kubernetes CLI
  3. Helm - For installing Ark components
  4. Node.js - For building the ark-cli tool
  5. Kind - For creating local clusters (which kind)

Step 0: Check existing cluster state

CRITICAL: Always check before creating or modifying clusters.

kubectl cluster-info 2>/dev/null
kubectl get pods -n default 2>/dev/null | head -10
kind get clusters 2>/dev/null

If a cluster is already running

Never silently destroy an existing cluster. It may have user data, demos, or in-progress work. Present options:

  • Option A: Reuse existing cluster — deploy Ark into it. Fastest, but overwrites current Ark state.
  • Option B: Create isolated cluster (recommended for e2e testing) — kind create cluster --name ark-e2e-test. Fully isolated, preserves existing cluster.
  • Option C: Replace existing cluster — delete and recreate. Only if user explicitly confirms.

Wait for user to choose, or if called by the build manager for e2e testing, default to Option B.

Step 1: Create cluster

Default mode (existing cluster or new ark-cluster)

kind create cluster --name ark-cluster

Isolated e2e testing mode

kind create cluster --name ark-e2e-test
kubectl config use-context kind-ark-e2e-test

Configure kubeconfig (if running inside Docker/DinD)

CONTROL_PLANE_IP=$(docker inspect -f '{{range.NetworkSettings.Networks}}{{.IPAddress}}{{end}}' <cluster-name>-control-plane)
kind get kubeconfig --name <cluster-name> --internal | sed "s/<cluster-name>-control-plane/$CONTROL_PLANE_IP/g" > ~/.kube/config
kubectl cluster-info

Read the full file on GitHub · 143 lines

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. 9d ago First seen · 143 lines · 54 tokens per session scan C d4769315d870

Subscribe to this mod's changes

ark-setup-cluster is a skill published in the GitHub repository mckinsey/agents-at-scale-ark (423 stars, last pushed yesterday), licensed Apache-2.0. It adds 54 tokens to every session and 1,093 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 1 finding (reaches for credential files). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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