Get Performance Score

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

The description adds no behavioral information beyond the annotations. It does not state that the tool fetches a live URL, runs a Lighthouse audit, or that it may take time or require network access. With readOnlyHint and openWorldHint already provided, the description contributes nothing extra.

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 efficient sentence with no wasted words. It is appropriately concise for the tool's simplicity, though it is not front-loaded with any additional context because there is none.

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 simple two-parameter tool with an output schema, the description is minimally adequate but lacks key contextual details such as what constitutes a 'performance score' (e.g., Lighthouse metric), prerequisites like URL accessibility, or any potential variability. Given the existence of siblings, it is not sufficiently complete to guide correct selection.

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% as both 'url' and 'device' are described in the input schema. The description adds no additional meaning about the parameters or their usage, so the baseline of 3 is appropriate.

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 uses a specific verb ('get') and resource ('performance score for a website'), making the intent clear. However, it does not differentiate from nearby siblings like get_core_web_vitals or get_lcp_opportunities, which also relate to performance metrics, so there is a mild ambiguity.

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?

There is no guidance on when to use this tool versus alternatives such as get_core_web_vitals or analyze_resources. No exclusions or recommended contexts are provided, leaving an agent to infer the appropriate choice.

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