chrome_page_load_summary

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

Annotations already indicate readOnlyHint=true, destructiveHint=false, idempotentHint=true. The description reinforces this with 'Read-only' and adds valuable behavioral details: parameter behavior (limit cap at 5000, max_string_len), output format (metadata-first, row_count, truncated flags), and empty result handling. This goes well beyond the annotations.

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 appropriately sized with each sentence providing useful information. It is front-loaded with the core purpose. Minor repetition (e.g., 'Read-only' echoed from annotations) but overall efficient and well-structured.

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?

Despite having no output schema, the description explains the output format (metadata-first JSON, row_count, truncated flags) and covers edge cases (empty result meaning no navigations occurred). It provides alternative tool for sub-event timings. This is fairly complete for a tool of moderate complexity.

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?

Schema coverage is 100%, so baseline is 3. The description adds meaning by specifying default values (limit defaults to 100, max_string_len unset preserves full strings), caps (limit capped at 5000), and that parameters accept both numbers and numeric strings. This extra context raises the score to 4.

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 each page navigation in a Chrome trace with specific metrics (navigation id, URL, timestamps, FCP, LCP, DCL, load). It differentiates from using execute_sql on the underlying module, but does not explicitly contrast with sibling tools like chrome_page_load_resource_summary, so it scores 4 rather than 5.

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 explicitly lists when to use (comparing page-load timings, finding slow loads, baselining web-vitals) and when not to use (non-Chrome traces). It provides a clear alternative (execute_sql for sub-event timings), meeting all criteria for a top score.

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