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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description nevertheless adds a genuine behavioral disclosure: it will not fabricate zeros for pages absent from the current response, which tells the agent how missing data is handled. It stops short of explaining the comparison mechanics or pagination/limit 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?

Two sentences, front-loaded with the defining condition, and the second sentence earns its place by clarifying an edge case. No filler or restatement of the name.

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?

With 9 parameters at zero schema coverage and no explanation of how 'worse' or 'fell' is computed, the agent cannot confidently supply the required comparison dates. The existing output schema covers return values, but the input-side gap is large for a derived analytics tool.

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 9 parameters, so the description carries the full burden. It explains none of them: no mention of startDate/compareStartDate/compareEndDate, device, country, searchType, or limit. Only a faint implication of comparison exists.

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 defines the resource (pages) by a precise three-part condition: worse position, falling clicks, or disappearance from the current response. This distinguishes it from siblings like top_pages and quick_wins, though it never names an 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?

There is no when-to-use or when-not-to-use guidance, and no mention of how it relates to compare_periods or top_pages. The agent must infer that a comparison window is needed to produce 'worse' or 'fell'.

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