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/chankov/agent-fleet/web-performance-auditorgit clone --depth 1 https://github.com/chankov/agent-fleetWhat 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 | $0.00045 | $0.02967 |
| Opus 5 | $0.00023 | $0.01484 |
| Sonnet 5 | $0.00009 | $0.00593 |
| Haiku 4.5 | $0.00005 | $0.00297 |
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
97% identical to web-performance-auditor — 8 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 — 193 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 · 193 lines · 45 tokens per session scan A 9b8a841a488b
web-performance-auditor is an agent published in the GitHub repository chankov/agent-fleet (10 stars, last pushed 6d ago), licensed MIT. It adds 45 tokens to every session and 2,967 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 97% identical to web-performance-auditor, differing in 8 lines, and is treated as a copy.
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