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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's added value is the scoring methodology: brand-level signals preferred, fallback to item-trend aggregation, with a per-result trend_source discriminator. That tells the agent how to interpret and trust results, which is genuine behavioral context beyond the annotations.

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 resource and ranking criterion, then the methodology. Dense but every clause carries information; no filler or restated title.

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?

An output schema exists, so return shapes need not be spelled out, and the description still usefully names the trend_source field. Combined with the methodology and filter scoping, the definition is complete enough for a zero-required-parameter read tool, with only the untagged parameters as a residual gap.

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 only 25%, so the description should compensate more. It does clarify that 'category' and 'tier' act as optional narrowing filters on the trending set, but says nothing about 'limit' or the 'agent' self-identification block, leaving half the parameters explained only by the schema itself.

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 ranking basis: 'Hot and rising brands right now, ranked by brand trend status and score.' The brand-level scope implicitly distinguishes it from item-level siblings like 'trending' and lookup siblings like 'search_brands', 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?

The optional category/tier filtering is described, which implies when this tool is appropriate (browsing trending brands within a segment). However, there is no explicit guidance on when to use this versus 'trending', 'search_brands', or 'similar_brands', leaving the agent to infer routing.

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