webtool_web_vitals

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

No annotations exist, so the description must cover behavioral traits. It mentions using Performance Observer API and providing insights, implying a non-destructive read operation. However, it omits critical details like whether the tool actually loads the URL (likely yes), potential impact on the server, or any rate limits. The description is adequate but could be more explicit about safety.

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?

Two concise sentences deliver the core purpose and method with zero redundancy. The first sentence focuses on actionable output (identify problematic elements), and the second adds technical credibility. Every word serves a purpose.

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?

Without an output schema, the description must clarify return values. It vaguely promises 'detailed insights' but doesn't specify structure (e.g., list of elements with metrics, scores, or suggestions). Given the tool's complexity (12 params, nested objects), this omission leaves agents uncertain how to use results.

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 the description need not elaborate each parameter. The description adds context by naming the underlying API (Performance Observer) and the goal of identifying problematic elements, which aids understanding. However, it doesn't enhance parameter meaning beyond the schema's already comprehensive descriptions, earning a baseline 3.

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 analyzes Core Web Vitals metrics and lists specific metrics (LCP, CLS, FID/INP, TTFB), making it distinct from sibling performance tools like webtool_lighthouse which focus on broader audits. The verb 'Analyze' and resource 'Core Web Vitals metrics' are specific and unambiguous.

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?

No guidance is provided on when to use this tool versus alternatives like webtool_lighthouse or webtool_performance_test. The description implies usage for web vitals analysis but lacks explicit context for selection, such as scenarios requiring element-level identification or non-Lighthouse approaches.

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