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.
npx agentmods add skills/sukirman1901/frontend-expert/fe-devtoolsnpx skills add sukirman1901/frontend-expert --skill fe-devtoolsgit clone --depth 1 https://github.com/sukirman1901/frontend-expertWrote 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/sukirman1901/frontend-expert/fe-devtools)<a href="https://agentmods.dev/skills/sukirman1901/frontend-expert/fe-devtools"><img src="https://agentmods.dev/badge/skills/sukirman1901/frontend-expert/fe-devtools.svg" alt="Measured on agentmods" 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 | $0.00058 | $0.00618 |
| Opus 5 | $0.00029 | $0.00309 |
| Sonnet 5 | $0.00012 | $0.00124 |
| Haiku 4.5 | $0.00006 | $0.00062 |
Grade A, and why
fe-devtools 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 4d 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 — 63 lines — stays where its author put it; the contents beside it link to each section on GitHub.
FE DevTools
Overview
Use browser/tooling evidence when available — don’t invent Lighthouse scores. Pair with web-performance, accessibility, and frontend-testing.
When to use
/test-uior ship checks when tooling exists in the project- User asks for Lighthouse, axe, Network, Layout shift, Coverage
- Design/perf audit needs measured Performance or Accessibility scorecard rows
- Verifying no horizontal overflow / focus order with real viewport tools
When to skip
- No runnable app / static markdown-only change
- User wants theory-only advice with no environment
- Pure token rename with no UI surface
MUST vs optional
| Check | MUST when | Optional |
|---|---|---|
| Responsive viewports | Layout UI ship (320/768/1024/1440) | — |
| Keyboard / focus | Interactive forms, dialogs, drawers | — |
| axe / a11y scan | /test-ui, /design deep, or user asks |
Quick source-only audit |
| Lighthouse / CWV | Perf ask, public landing, /design deep with app running |
Tiny internal chrome tweak |
| Network waterfalls | Suspected overfetch / huge assets | Default CRUD form |
| Layout / CLS | Animations, fonts, images without dimensions | Static settings copy |
Rule: Never fabricate scores. If tools didn’t run → scorecard = not evaluated.
Workflow
- Confirm target — URL/route or local preview command
- Viewport — resize or device mode; note Responsive Conventions
- A11y — axe or equivalent; fix Critical/High (labels, contrast, names)
- Perf — Lighthouse or Web Vitals extension on key route; note LCP/INP/CLS risks
- Network — flag obvious huge JS/CSS/images on first load
- Report — tool · metric · value · source; hand remediations to
web-performance/accessibility/ build skills
Checklist
- Did not invent Lighthouse/axe numbers
- Viewport evidence for layout ships
- A11y scan when MUST (or waiver documented)
- Perf metrics only when tool ran or explicitly source-level risks
- Findings mapped to skills (not dumped as vague “optimize”)
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.
- 4d ago First seen · 63 lines · 58 tokens per session scan A e8983a0bd59b
fe-devtools is a skill published in the GitHub repository sukirman1901/frontend-expert (10 stars, last pushed yesterday), licensed MIT. It adds 58 tokens to every session and 618 once invoked, about $0.0003 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 2026-08-31.
Other skills, from other repositories
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
brainstorming
You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.
auto-perf-optimize
Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.
chat-perf
Run chat perf benchmarks and memory leak checks against the local dev build or any published VS Code version. Use when investigating chat rendering regressions, validating perf-sensitive changes to chat UI, or checking for memory leaks in the chat response pipeline.
chat-pet-sprite-creation
Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.
cpu-profile-analysis
Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…