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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful operating context beyond that: the 24-hour default window and a hard cap of at most 25 returned trends, which an agent needs to avoid misjudging result completeness.

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, all front-loaded: purpose and metrics first, then routing/filtering guidance, then scope limits. No filler and no repetition of the tool 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 no output schema, the description carries the burden of describing returns; it states the metrics available (volume, velocity, growth) and the 25-item cap, which is nearly sufficient. It does not describe the shape of a single trend entry, leaving a small gap for an agent relying on the response.

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% and the schema already explains limit ranges, period values, sort_by semantics and category lookup. The description largely restates these ('sort_by=velocity returns the fastest-accelerating topics first', the 24h default) rather than adding new semantics, so the baseline 3 applies.

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?

Names a specific verb and resource — trending topics on social platforms — and immediately qualifies the output with 'measured volume, velocity and growth', which distinguishes it from sibling readers like get_trend (single trend) and search_trend_insights. An agent can tell what it returns without opening the schema.

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?

Gives clear positive context ('use to find what is rising in a category or around a brand, product or competitor') and routes to list_trend_categories for valid category names. It stops short of saying when NOT to use it versus get_trend or search_trend_insights, so the disambiguation is only partial.

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