get_pagespeed_insights

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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds that it returns Lighthouse lab data plus CrUX field data, but omits rate limits/quotas (the PageSpeed API is quota-limited), API key or auth requirements, and latency expectations for an open-world call.

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?

Short and front-loaded, with the core action stated first and the return data immediately after. The Args block is compact and earns its place, though it partially restates schema fields.

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?

An output schema exists, so return-value explanation is not required, and annotations cover safety. The description covers purpose and all three parameters adequately; the only meaningful omission is guidance on when to prefer this tool over the overlapping lighthouse/CrUX siblings.

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 description coverage is 0%, so the description must carry the parameter burden, and it largely does: it identifies url as a full page URL, strategy as mobile or desktop, and categories as comma-separated Lighthouse categories. It does not enumerate valid category values or state defaults, leaving some detail to the 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?

States a specific verb and resource ('Run Google's PageSpeed Insights API for a URL') and clarifies the data returned (Lighthouse lab data plus Chrome UX Report field data). However, it does not differentiate itself from closely related siblings such as run_lighthouse_audit, audit_live_site, or get_core_web_vitals, which overlap in function.

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 gives no when-to-use guidance, no prerequisites, and never names an alternative tool. With siblings like run_lighthouse_audit and get_core_web_vitals offering overlapping capability, the absence of routing guidance is a real gap.

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