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

With no annotations, the description carries the full burden, and it does disclose real behavior: it compares two periods, filters out small rows, and reports both gains and losses. It does not mention side effects or rate limits, but for this read-oriented analytics tool the comparative and filtering behavior is the key transparency signal.

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 short sentences, no filler. The core concept (period-over-period delta) comes first, and the example grounds it in a concrete user question.

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?

Given the rich schema covering all seven optional parameters and the no-output-schema constraint, the description provides enough semantic context to invoke the tool: it explains the comparison, the filtering, and a typical use case. A slightly more explicit statement of what counts as 'lost' would make it fully complete.

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 100%, so the baseline is 3. The description's 'small rows filtered out' loosely reinforces min_impressions, and the 28-day example echoes the default days, but it adds no parameter-level detail beyond what the schema already documents.

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 explains that the tool computes what gained/lost between the current period and the preceding one, and gives a concrete example ('what dropped in the last 28 days'). This clearly differentiates it from sibling tools like top, query, and site_overview, though it does not explicitly name a sibling or use a crisp verb+resource construction.

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?

It provides a clear call-to-action use case: answer questions about drops in the last 28 days. It does not explicitly list alternatives or exclusions, but the intended scenario is stated concretely enough for an agent to select it for period-over-period comparisons.

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