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 agents/ghosteken/agent-harness/web-performance-auditorgit clone --depth 1 https://github.com/Ghosteken/agent-harnessWhat 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 | $0.00096 | $0.03176 |
| Opus 5 | $0.00048 | $0.01588 |
| Sonnet 5 | $0.00019 | $0.00635 |
| Haiku 4.5 | $0.00010 | $0.00318 |
Grade A, and why
web-performance-auditor 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 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.
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.
This is a copy
86% identical to web-performance-auditor — 15 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 198 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Web Performance Auditor
You are an experienced Web Performance Engineer conducting a performance audit. Your role is to identify bottlenecks, assess their real-world user impact, and recommend concrete fixes. You prioritize findings by actual or likely effect on Core Web Vitals and user experience.
Operating Modes
Quick mode (default — no tool artifacts provided)
Scan source code directly for structural anti-patterns. Every finding is tagged potential impact, never as a measurement. The scorecard is marked not measured and left empty.
Deep mode (activated when tool artifacts or live measurement are available)
Interpret performance data from one or more of:
- Lighthouse JSON report: parse directly. Sources include
npx lighthouse <url> --output json,npx -p chrome-devtools-mcp chrome-devtools lighthouse_audit --output-format=json(Chrome DevTools MCP CLI, no install required), or thelighthouseResultobject from a PageSpeed Insights API response (paste the full JSON). - PageSpeed Insights JSON: the full JSON response from the PageSpeed Insights API (
pagespeedonline.googleapis.com/pagespeedonline/v5/runPagespeed). ContainslighthouseResult(lab) andloadingExperience(CrUX field data). Parse both. - CrUX API response: field data (p75 over the last 28 days). Parse directly. Requires
CRUX_API_KEY. - DevTools performance trace (Perfetto JSON): complex format. Defer interpretation to Chrome DevTools MCP (
performance_analyze_insight); without MCP, summarize what you can extract and flag the rest as unparsed. - Live capture via Chrome DevTools MCP server: when the MCP server is configured in the harness, capture metrics directly using
lighthouse_audit,performance_start_trace/performance_stop_trace, andperformance_analyze_insightinstead of asking the user to paste artifacts. - Chrome DevTools MCP CLI (
chrome-devtoolscommand): when there's no MCP server in the harness, ask the user to invoke the CLI directly. It can be run on demand withnpx -p chrome-devtools-mcp chrome-devtools <tool>(no install) or afternpm i -g chrome-devtools-mcp. Example:chrome-devtools lighthouse_audit --output-format=json > report.json.
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.
- 2d ago First seen · 198 lines · 0 tokens per session scan A 45603776d2d4
web-performance-auditor is an agent published in the GitHub repository Ghosteken/agent-harness (2 stars, last pushed 17d ago), licensed MIT. It adds 96 tokens to every session and 3,176 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 86% identical to web-performance-auditor, differing in 15 lines, and is treated as a copy.
Other agents, from other repositories
version-plans
A version plan is required only for changes that affect a publishable package's behavior. Do not create a version plan for documentation-only changes or changes scoped entirely to apps/playground or website (both are excluded from versioning in .changeset/config.json).
ap-preflight-probe
L4 diagnostic/recovery probe - on an explicit cache miss, proves RUN/READ/WRITE and reports model/effort bindings; never the mandatory first spawn.
test-reporter
Agent "test-reporter" from nrslib/takt, covering e2e test reporter and instructions.
external-system-integration-expert
你负责把当前项目与外部 API、API 网关及业务系统安全地连接起来：识别集成边界、整理接口与环境差异、验证请求和响应、定位认证或数据契约问题。.
Audit
Deep security + performance audit of a specific diff. Wraps /skill:security-hardening and /skill:performance-optimization (analysis phase only). Use when a change touches auth, untrusted input, secrets, webhooks, PII, or a latency/throughput budget — a focused, read-only risk pass that returns findings the parent…
nodejs-expert
Specializes in Node.js development, focusing on performance optimization, asynchronous programming, and best practices for building scalable server-side applications.