chrome_page_load_summary

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

The description states it is read-only, operates on the loaded trace, and describes the empty result scenario. It also mentions that non-Chrome traces will error. With no annotations, this fully covers the behavioral traits.

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

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

The description is well-structured with clear sections: purpose, read-only hint, usage guidelines, don't-use, parameter note, and empty result explanation. Every sentence is informative and there is no fluff.

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

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

While the description lists the fields returned, it does not specify the output structure (e.g., list of records) or provide details on the data types beyond 'ms'. Given no output schema, slightly more detail would improve completeness.

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

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

There are no parameters, but the description adds meaning by explicitly stating 'Parameters: none — operates on the loaded trace,' clarifying the implicit input. This adds value beyond the empty schema.

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

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

The description clearly states the tool summarizes page navigation with specific metrics (navigation id, URL, FCP, LCP, DCL, load timings) in a Chrome trace. It distinguishes itself from sibling tools like chrome_main_thread_hotspots by focusing on page load timings.

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

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

The description provides explicit when to use (comparing load timings, finding slow loads, baselining) and when not to use (non-Chrome traces, sub-event timings; it recommends execute_sql as alternative). This is excellent guidance.

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