web-perf

1# Web Performance Audit
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3Your knowledge of web performance metrics, thresholds, and tooling APIs may be outdated. **Prefer retrieval over pre-training** when citing specific numbers or recommendations.
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5## Retrieval Sources
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7| Source | How to retrieve | Use for |
8|--------|----------------|---------|
9| web.dev | `https://web.dev/articles/vitals` | Core Web Vitals thresholds, definitions |
10| Chrome DevTools docs | `https://developer.chrome.com/docs/devtools/performance` | Tooling APIs, trace analysis |
11| Lighthouse scoring | `https://developer.chrome.com/docs/lighthouse/performance/performance-scoring` | Score weights, metric thresholds |
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13## FIRST: Verify MCP Tools Available
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15Discover available browser and performance tools before starting. Use the capabilities available for the requested audit. If trace tools are unavailable, continue any useful source or network analysis and state which measurements could not be collected.
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17If the user wants Chrome DevTools MCP setup, consult its [installation guide](https://github.com/ChromeDevTools/chrome-devtools-mcp#quick-start) and use the latest package version. Only change MCP configuration when setup is within the user's authorized scope; otherwise ask first. For clients using `command` and `args`, an example server entry is:
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19```json
20"chrome-devtools": {
21  "command": "npx",
22  "args": ["-y", "chrome-devtools-mcp@latest"]
23}
24```
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26## Key Guidelines
27…