browser_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 does not mention whether this operation is read-only, has side effects, requires authentication, or returns data. The agent learns nothing about the tool's runtime behavior.

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 short phrase, which is efficiently brief, but it is under-specified rather than concise. It fails to front-load any actionable information, such as requiring a URL or interpreting JSON output. The phrase barely earns its place.

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?

The tool has 3 parameters, no annotations, and no output schema, so the description must compensate for missing structural context. It does not explain what Web Vitals metrics are returned, how the session parameter affects behavior, or what the JSON output contains. The description is wholly inadequate for an agent to invoke this tool correctly.

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 100% description coverage for all three parameters (url, json, session). Although the descriptions are brief, they do exist. The tool description adds no additional meaning beyond the schema, so the baseline of 3 for full coverage is appropriate, but no value is gained from the tool description itself.

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 'Web Vitals metrics', which essentially restates the tool name 'browser_vitals' without adding specificity. It does not indicate what metrics are measured, whether it requires a URL, or what the output looks like. This is near-tautological and fails to distinguish from sibling tools.

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 vs siblings. The description offers no context for selecting browser_vitals over browser_profile, browser_trace, or browser_network. An agent receives no direction on appropriate use cases.

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