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

Annotations already declare read-only/idempotent/non-destructive, so safety is covered. The description adds real value beyond them: data provenance ('Metrics are copied from Search Console rows') and a unit clarification ('ctr is the API fraction from 0 to 1') that prevents a common misinterpretation of the metric.

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?

Three tight sentences, front-loaded with the resource and scope, followed by metric semantics and the default-window rule. No filler, though the 'copied from Search Console rows' clause is somewhat incidental.

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?

Output schema exists, so return values needn't be explained, and annotations cover the safety profile. Still, for a 7-parameter tool with 0% schema coverage, most filter parameters (device, country, searchType, limit) remain unexplained, leaving a real gap for correct 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?

Schema description coverage is 0% across 7 parameters, so the description carries the full burden. It only addresses the date parameters and ctr; limit, device, country, searchType, and siteUrl are left entirely undocumented in both schema and description.

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?

States a specific verb+resource: 'Top pages for one property and date range.' The resource (pages) is clear enough to distinguish it from the sibling top_queries, though the description never names that alternative explicitly.

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 line 'Omit dates to use the default 28-day window' gives a concrete usage rule for the date parameters, which is helpful. However there is no when-to-use-this-vs-siblings guidance (e.g. vs top_queries, performance_trends, or quick_wins), so the agent must infer selection from the resource name alone.

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