get_page_performance

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

No annotations are provided, so the description must cover behavioral traits. It accurately describes the output (specific metrics, top 20 resources). However, it does not mention any side effects, prerequisites (e.g., page must be loaded), or limitations (e.g., only works after page load). No contradictions.

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 two sentences, front-loads the purpose, and every sentence adds value. No redundancy or 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?

Given zero parameters and no output schema, the description is largely complete. It specifies the metrics returned and the environment. Minor omission: could clarify unit (e.g., milliseconds) or confirm the tool returns data from the current page state.

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?

The input schema has zero parameters, and schema coverage is 100%. According to the guidelines, 0 parameters yields a baseline of 4. The description adds no parameter info but compensates by clearly describing the return data.

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 gets page performance metrics, names the APIs used (Navigation Timing and Resource Timing), and lists specific metrics (TTFB, DOM timings, top 20 resources). This effectively distinguishes it from sibling tools like list_resources or inspect_request, which provide different detail.

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 states it works on both browsers and SPAs, implying its usage for page-level performance analysis. However, it does not explicitly guide when to prefer this tool over alternatives like list_resources or inspect_request, nor does it mention when not to use it.

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