chrome-audit-network

Navigate to a URL, collect Performance Resource Timing entries, filter/summarize, and optionally screenshot. Best for diagnosing slow page loads, unexpected API calls, or payload size issues.

Requires: Chrome DevTools MCP server running and connected.

Inputs

If filePath is omitted, auto-name: ./tmp/network-<sanitized-host>.png

sanitize(x): lowercase; keep a–z 0–9 - _; replace other chars with -.

Procedure

1. Navigate

mcp__chrome__navigate_page: { "url": "${input:url}" }

2. Clear existing timings

performance.clearResourceTimings();

3. Wait for activity

Wait ${input:duration} ms (or until network appears settled).

4. Collect resource entries

(() => {
  return performance.getEntriesByType('resource').map(e => ({
    name: e.name,
    initiatorType: e.initiatorType,
    transferSize: e.transferSize,
    encodedBodySize: e.encodedBodySize,
    decodedBodySize: e.decodedBodySize,
    duration: Math.round(e.duration),
    protocol: e.nextHopProtocol,
  }));
})()

5. Filter & analyze

• Apply ${input:filter} regex to name if provided.
• Group by initiatorType (fetch, xmlhttprequest, script, img, css, font, other).
• Sort by duration desc → top 10 slowest.
• Sort by transferSize desc → top 10 heaviest.

6. Screenshot (optional)

Resolve filePath to absolute path, create parent dirs, call mcp__chrome__take_screenshot.

Output Format

🧭 URL

${input:url} — audited at <timestamp>

📊 Summary

• Total requests: N
• By initiatorType: fetch: N, script: N, css: N, img: N, font: N, ...
• Filter applied: ${input:filter} or "none"

🐌 Slowest requests (top 10)

📦 Heaviest by size (top 10)

🖼 Screenshot

Saved: <absolute path> (if captured)

📋 Raw table (filtered)

Compact table of all matched requests: initiatorType | transferSize | duration | name

Notes

• transferSize = 0 usually means served from cache (304 or disk cache).
• HTTP/1.1 connections with many requests → consider HTTP/2 or bundling.
• Headers and status codes are not available from Performance entries; for those, use targeted fetch() calls via mcp__chrome__evaluate_script.
• For SPA flows, navigate to the route first, then clear timings before triggering the specific action.

Common Mistakes

• Forgetting to clear timings first — entries from previous navigations pollute results.
• Too short a duration — lazy-loaded resources and deferred API calls may not appear.
• Treating transferSize=0 as missing — it means cached, not absent.