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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so safety is covered. The description adds value by disclosing the return shape (countries, first seen, last day seen, peak traffic), which matters since there is no output schema.

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?

One dense sentence, front-loaded with the action and scope, then the payoff (returned fields). No filler, though the return-field list makes it slightly heavy for a single clause.

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?

Covers the return fields well given no output schema, and annotations cover behavior. But with 0% schema description coverage, geo and days semantics are missing, which is a meaningful gap an agent must infer.

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 0% and the description only loosely maps to the params: 'topic' for q, 'countries' hints at geo, and 'last 30 days' hints at days. It never explains that geo is a country filter or that days overrides the default window, leaving two of three params undocumented.

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?

Clear verb+resource: 'Search the last 30 days of trending searches for a topic.' The 30-day historical window distinguishes it from siblings like trending_now and trending_day, though no sibling is named 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?

Usage is implied by the temporal framing ('last 30 days'), which suggests a historical/lookup use case versus live tools, but there is no explicit when-to-use or when-to-prefer-a-sibling guidance.

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