Content
88%Weight 40%Scale 1-5Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
A strong operational skill: check-first idempotent steps, fully executable commands with per-OS variants, explicit re-checks, error-recovery branches, and a green-criteria smoke test. The only weaknesses are verbosity in section 4's justifications and rationale prose that would sit better in a reference file than the main body.
Suggestions
Trim section 4's war-story justification ('went unnoticed for two weeks, costing ~25 minutes of package downloads on every review') to one sentence — the rule 'build unconditionally; Docker's layer cache already answers the question' stands on its own.
Move the pnpm-store internals (read-only layer, ~2.3 GB copy-up, per-host sharing) and the section 6 security mitigation (store poisoning risk) into a one-level-deep reference file (e.g. references/sandbox-internals.md), keeping only the actionable line in SKILL.md.
State the ✅/❌ reporting requirement from step 5 once in a closing line rather than only inside the smoke-test section, so partial failures of earlier steps are reported in the same format.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The body is largely operational facts Claude could not infer (fish shell, BTF-mismatch reboot, minimal build context, read-only store copy-up), but section 4 pads with a war-story justification — 'which is exactly how an image predating the pnpm-store warming went unnoticed for two weeks, costing ~25 minutes' — and a paragraph of copy-up/pnpm-store internals that could be trimmed to their actionable core. Not 5 (some tokens don't earn their place); clearly above 3 (no explanation of concepts Claude already knows). | 4 / 5 |
Actionability | Every step gives copy-paste-ready commands: the runsc detection one-liner, the full gVisor apt/gpg install block, 'sudo modprobe veth', 'bash tools/review-sandbox/build-image.sh', the smoke test with the RUNTIME variable explicitly defined per-OS ('--runtime=runsc on Linux, "" on macOS'), and the exact prune invocations. Common cases and failure cases are both covered. | 5 / 5 |
Workflow Clarity | Six clearly sequenced idempotent steps, each with a check-first command, explicit re-validation ('Then re-check the runtime line above'), error-recovery branches (veth BROKEN → modprobe; BTF mismatch → reboot + persist via /etc/modules-load.d), and a final smoke test with explicit pass criteria ('Green when: the kernel is NOT your host kernel, and node/java/dotnet report versions') and a per-step ✅/❌ reporting requirement. | 5 / 5 |
Progressive Disclosure | The numbered section structure is clean and the ~100-line body needs no bundle files (none exist; referenced paths tools/review-sandbox/build-image.sh and .claude/tools/sandbox are repo tooling, not skill references). But the rationale prose in sections 4 and 6 (the two-week anecdote, the pnpm-store poison mitigation, the host-naming/`--host` explanation) is inline commentary that belongs in a one-level-deep reference. Good structure, minor organization gaps — anchor 4, not 5. | 4 / 5 |
Total | 18 / 20 Passed |