devtools_performance

Performance panel. start/stop a trace recording (Chrome trace format, opens in DevTools Performance and Perfetto). stop returns a summary: time by category, long tasks with their heaviest children, script time by URL, observed LCP/FCP/CLS, user timings. search finds trace events by name/args. compare diffs two recordings. vitals reads live Web Vitals (LCP, CLS, INP, FID, FCP, TTFB, long tasks) observed in the page since the session started. metrics returns Chrome runtime metrics.

Parameters

integer

Target tab id from browser_tabs, which lists tabs across all windows. Defaults to the agent’s most recently opened usable tab, or the only usable tab. Otherwise select a listed tabId.

enum

required

One of: start, stop, search, compare, vitals, metrics, list.

string[]

Trace categories (default: devtools timeline + v8)

boolean

start: reload the page right after tracing begins (page-load profile)

string

compare: second recording

string

boolean

number

integer

Pagination offset, default 0 Range: 0 to ….

integer

Page size, default 50 Range: 1 to 500.

Example

{
  "tabId": 1234,
  "action": "start",
  "reload": true,
  "screenshots": false
}

{
  "tabId": 1234,
  "action": "stop"
}

Live Web Vitals

{
  "tabId": 1234,
  "action": "vitals"
}

Browser automation

Developer tools

devtools_performance

Parameters

Example

​Parameters

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Parameters

Example