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

Annotations already declare idempotentHint=true and destructiveHint=false, and the description adds that results are ranked by performance. However, operational behaviors like platform fallback paths (rubric_version) and the timestamp exclusion on TikTok rows live only in the parameter descriptions, not the main description. This keeps transparency at the baseline.

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?

The description is four sentences with the core action front-loaded. There is minor redundancy between 'example videos' in the first sentence and 'example URLs' in the second, but the length is appropriate and the 'Use when' cue is placed early enough to be useful.

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?

The full definition benefits from an output schema and exhaustive parameter descriptions, so an agent has the details needed to call this correctly. The description itself slightly under-serves by miscounting the niche enum (17 vs 18) and omitting the Instagram-specific requirement that query becomes mandatory, though this is documented in the schema.

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 schema carries full parameter semantics. The description's example of angle narrowing ('postpartum strength' within Fitness) mirrors the query parameter's own description and adds no new information.

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 opens with a specific verb and resource: 'Find proven viral templates in a niche with example videos.' It promptly enumerates the concrete outputs (hook patterns, format structures, average views, example URLs), which distinguishes it from sibling tools like search_videos or predict_virality. The only blemish is stating 17 niches while the schema enum lists 18, but this does not obscure the tool's purpose.

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?

'Use when the user asks what's working in a niche or wants concrete copyable structures' gives clear, actionable context for when to invoke the tool. It stops short of naming specific alternatives or stating when not to use it, so it misses the top score.

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