pagespeed_core_web_vitals

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

No annotations provided. Description implies a read operation with no destructive effects. Lists metrics returned, adding some transparency, but does not disclose rate limits, authentication needs, or behavior when URL is not accessible.

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?

Single sentence efficiently conveys purpose and key details (metrics, device types). No superfluous words; front-loaded with essential information.

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?

No output schema provided. Description fails to specify the structure of the response (e.g., whether metrics are returned per device or combined). Lacks detail on what the agent receives after invocation.

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?

One parameter 'url' with schema description 'The URL to analyze' and 100% schema coverage. Description adds no further semantics (e.g., URL format, requirements). Baseline 3 applies as schema covers parameter fully.

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?

Description clearly states it retrieves Core Web Vitals for both mobile and desktop, listing specific metrics (LCP, FID, CLS, etc.). Among sibling tools like 'pagespeed_analyze', this distinguishes itself by focusing solely on Core Web Vitals.

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 on when to use this tool vs. alternatives like 'pagespeed_analyze'. Does not mention prerequisites, limitations, or scenarios where another tool would be more appropriate.

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