get_web_vitals

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states what the tool retrieves (performance metrics) without clarifying whether the operation is read-only, whether it triggers measurement side effects, or the exact structure of the returned data. For a tool that interacts with browser performance, more context on side effects or measurement scope is needed.

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?

A single, direct sentence that immediately conveys the tool's purpose. No filler, no redundant wording, and the most important information (metrics retrieved) is front-loaded. Excellent structure.

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 the low complexity (no parameters, no output schema), the description covers the core function adequately. However, it omits details about the return structure or whether metrics are from the current page, which could be relevant for an agent. Overall, it is mostly complete for a simple getter.

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 tool has zero parameters, so schema coverage is trivially 100%. Per the rubric, a zero-parameter tool receives a baseline score of 4, and the description has no additional parameter details to provide since none exist.

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's action ('Get') and resource ('Core Web Vitals (LCP, FID, CLS) and other performance metrics'). It specifies concrete metrics (LCP, FID, CLS), distinguishing it from sibling tools that handle network or DOM data. The phrase 'other performance metrics' introduces slight ambiguity but does not undermine overall purpose clarity.

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 no explicit guidance on when to use this tool versus alternatives. The intended use is implied by the tool's name and description, but there are no stated exclusions, prerequisites, or comparisons to sibling tools like get_slow_components or detect_memory_leaks. This is a clear but implicit usage indication.

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