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. It discloses that the tool returns p75/p95 values and quality ratings, but does not explain whether it is read-only, what time window is used, how the route parameter behaves when omitted, or any aggregation logic. These are significant gaps for a metrics tool without annotation support.

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 a single dense sentence that front-loads the source ('[probe RUM]') and packs all key details—metric names, percentiles, and rating categories—without any wasted words. It is highly scannable and information-efficient.

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?

For a tool with no output schema and no annotations, the description explains the core returned metrics and ratings, but omits output structure, time range, and behavior of the optional route parameter. Given the tool's moderate complexity and the lack of structured support, the description is adequate but leaves notable gaps that an agent would need to infer.

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 schema provides descriptions for service and namespace, but not for route. The description only mentions 'per route' without explaining the route parameter's format, default, or whether it is required. With schema coverage at 67%, the description fails to compensate for the undocumented route parameter, and adds no new meaning for service or namespace beyond 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?

The description states a specific verb and resource: it retrieves Core Web Vitals (LCP, INP, CLS, FCP, TTFB) at p75/p95 per route, with quality ratings. This is clearly distinct from siblings like get_golden_signals or get_page_views, which target other metric sets.

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 '[probe RUM]' prefix hints at a data source, but there is no mention of when to prefer this over get_page_load_breakdown or get_browser_api_latency, nor any conditions or exclusions.

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