chrome_startup_summary
Summarize Chrome startup events to analyze time to first visible content and launch causes like NEW_WINDOW or CMD_LINE for cold start performance regressions.
Instructions
Summarize Chrome browser startup events: id, name, launch_cause, startup_duration_ms (first_visible_content_ts - startup_begin_ts), browser_upid. Read-only.
Use when: measuring time-to-first-visible-content for cold starts, comparing launch causes (NEW_WINDOW vs CMD_LINE vs RESTORE_SESSION), regressing startup performance.
Don't use for: non-Chrome traces (will error). Browser-process work during steady state is covered by chrome_main_thread_hotspots.
Parameters: optional limit (default 100, capped at 5000) and max_string_len. Operates on the loaded trace.
Output: metadata-first JSON; row_count exact; truncated=true means more rows exist; string_truncated=true means shortened text.
Empty result: trace started after the browser was already running (most cases — startup is captured only when tracing began before launch).
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Optional max rows to return. Defaults to 100 and is capped at 5000. Must be > 0 when set; accepts both numbers and numeric strings. | |
| trace_id | No | Optional trace id returned by `load_trace`. Omit to use the active trace. | |
| max_string_len | No | Optional per-string-cell character cap applied to returned Chrome-tool rows only. Unset preserves full strings for precision; accepts both numbers and numeric strings. Must be > 0 when set. |