Measure page speed

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

Discloses significant behavioral traits beyond the readOnlyHint annotation: distinct analysis handling, caching behavior, time expectations, honest reporting, and JSON output. The description thoroughly explains how the tool behaves and why, adding substantial context beyond annotations.

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 information-dense and front-loaded with the core purpose. It is somewhat long but every sentence adds behavioral or usage value. Could be slightly more terse, but the structure is logical and easy to follow.

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 read-only tool with no output schema, the description explains the return value ('report and JSON') and covers key behaviors like median reporting and time constraints. It lacks a detailed breakdown of the report structure, but is complete for the tool's complexity.

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%, so baseline is 3. The description adds value by explaining the runtime implications (runs=5 takes ~150s), the warning about runs=1, and clarifying that 'distinct' analyses are used. This goes beyond the schema descriptions.

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 measures a page with Google PageSpeed Insights and reports the median of several distinct analyses with min-max spread. This specific verb+resource+methodology distinguishes it from siblings like 'diagnose' or 'field_data'.

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?

Provides explicit usage guidance: warns against setting runs=1 for speed, explains the ~150s cost for runs=5, and notes that requesting harder won't speed it up. However, it doesn't explicitly name alternatives or state when to prefer this over sibling tools.

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