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chrome_page_load_resource_hotspots

Read-onlyIdempotent

Identify and rank slow resource requests during page loads by analyzing URL-bearing slices with timing and overlap details. Use to drill into problematic URLs after a summary.

Instructions

Rank URL-bearing Chrome resource/request slices in a page-load/raw window. Returns timing, overlap, process/thread/machine_id, URL. Use after chrome_page_load_resource_summary to drill into slow URL slices. Filters: page_load/window, min_dur_ms default 50, limit, max_string_len. slice_duration_status='incomplete_duration' means dur=-1; overlap is measured to window end or trace_end().

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
end_ts_nsNoOptional raw trace timestamp upper bound in nanoseconds, exclusive. This uses the same unit as the returned `ts` column. ANDs with any page-load window.
limitNoOptional max rows to return. Defaults to 100 and is capped at 5000. Must be > 0 when set.
max_string_lenNoOptional per-string-cell character cap applied to returned rows only. Unset preserves full strings for precision; accepts both numbers and numeric strings. Must be > 0 when set.
min_dur_msNoOptional minimum resource-like slice duration in milliseconds. Defaults to 50 ms. Pass 0 to see all matching resource slices.
navigation_idNoOptional Chrome navigation id used to scope resources to one navigation phase. Matches `chrome_page_loads.navigation_id`. Mutually exclusive with `page_load_id`. If set without `phase`, defaults to `navigation_to_fcp`.
page_load_idNoOptional page-load id used to scope resources to one navigation phase. Matches `chrome_page_loads.id`. Mutually exclusive with `navigation_id`. If set without `phase`, defaults to `navigation_to_fcp`.
phaseNoOptional page-load phase window. If set without `page_load_id` or `navigation_id`, uses the latest page load in the trace. Values: navigation_to_fcp, navigation_to_load, dcl_to_fcp, fcp_to_load.
start_ts_nsNoOptional raw trace timestamp lower bound in nanoseconds. This uses the same unit as the returned `ts` column. ANDs with any page-load window.
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, destructiveHint, idempotentHint. Description adds value by disclosing that 'incomplete_duration' means dur=-1 and how overlap is measured, which are key behavioral details.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Four sentences, front-loads purpose and output, includes usage guidance and a behavioral note. Efficient but could be better organized.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Describes output fields partially (timing, overlap, etc.) and usage flow, which compensates for missing output schema. Omits details on ranking metric but adequate for drilling into slow slices.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema already covers all 8 parameters with descriptions (100% coverage). Description summarizes filters but adds little new semantic meaning beyond schema defaults and phrasing.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Explicitly states it ranks URL-bearing resource slices, returns specific columns (timing, overlap, process/thread/machine_id, URL), and specifies its place after chrome_page_load_resource_summary, distinguishing it from siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Clear guidance: 'Use after chrome_page_load_resource_summary to drill into slow URL slices.' Provides context but no explicit when-not-to-use or alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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