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chrome_page_load_resource_summary

Read-onlyIdempotent

Summarizes URL-level Chrome resource requests for page-load windows, returning max overlap and attribution evidence. Use before resource hotspots for slow FCP or load events.

Instructions

URL-level Chrome resource/request summary for a page-load/raw window. Returns URL key, slice/process/priority sets, first/last/span, max_overlap_ms, summed_overlap_ms, pct_of_window, example_slice_id, and attribution evidence. Use before chrome_page_load_resource_hotspots for slow FCP/load; rank by max overlap because summed overlap can double-count layered slices.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
end_ts_nsNoOptional raw trace timestamp upper bound in nanoseconds, exclusive. 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_overlap_msNoOptional minimum per-URL max overlap in milliseconds. Defaults to 50 ms.
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. ANDs with any page-load window.
url_groupingNoURL grouping strategy. Defaults to full URL; use without_query to merge signed/nonce query variants of the same endpoint.

Tool Definition Quality

A4.2/5.0
Behavior4/5

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

Annotations already declare readOnlyHint, destructiveHint, idempotentHint. The description adds value by detailing the return fields, mentioning the overlap metrics, and warning about double-counting. No contradictions with annotations.

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

Conciseness5/5

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

Three succinct sentences covering purpose, usage context, and a ranking tip. No wasted words; front-loaded with key information.

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?

Given the complexity (9 parameters, no output schema), the description provides a good overview of the tool's output fields and use case. It could mention default limit or behavior when no parameters are set, but the param descriptions cover those details.

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 coverage is 100%, so the schema already documents all 9 parameters. The description adds no additional parameter-level meaning beyond what the schema provides.

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?

Clearly states it provides a URL-level summary of Chrome resource/request data for page-load or raw windows. Lists the specific fields returned and explicitly mentions it should be used before the sibling tool `chrome_page_load_resource_hotspots`, distinguishing its purpose.

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?

Gives explicit guidance to use this tool before `chrome_page_load_resource_hotspots` for slow FCP/load, and advises ranking by max overlap. However, it does not discuss when to choose other sibling tools like `chrome_page_load_summary` or `chrome_main_thread_hotspots`.

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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