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

Annotations already declare readOnlyHint=false, destructiveHint=true, and openWorldHint=true, so the non-free, side-effecting nature is flagged structurally; the description usefully confirms the cost model ('Costs SEO add-on credits; top up → Add-ons'). It does not, however, cover rate limits, what happens on refresh, or per-credit costs.

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 short, front-loaded sentences with no filler; the core capability leads and cost/upsell trails. The trailing 'top up → Add-ons' is slightly promotional but still actionable.

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 need not be described. Given the low schema coverage, however, the parameter gap is the main weakness; the description is otherwise complete for a read-style analytics call with a disclosed cost.

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% for all three parameters, so the description must compensate. It adds one real constraint ('up to 5 keywords') but leaves 'refresh' and 'location' entirely undefined in both schema and prose.

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 resource and operation: Google Trends interest-over-time and average seasonality data for up to 5 keywords. This is clearly distinguishable from adjacent siblings such as seo_keyword_research or keyword_planner, which do not return time-series interest 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?

It gives an implied use case ('to time ad campaigns and content around demand peaks'), which is genuine context, but never states when NOT to use it or names an alternative among the many keyword siblings. Usage is inferred rather than directed.

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