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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered; the description adds ordering (sorted by popularity), the shape of each result (example clip, required photos, credit price), and the no-query default. It does not mention result caps or how filters combine, which is a minor gap for a 5-param search.

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?

Front-loaded with purpose, then usage, then behavioral detail, ending with the recommended follow-up action. The example lists in the first sentence are somewhat padded, but each sentence still carries distinct information.

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-value explanation is a bonus rather than a requirement; the description nonetheless covers results, cost model, and next step. What is missing is modest: how many results to expect and how limit interacts with popularity sorting.

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?

With 60% schema coverage, the description adds real meaning: it maps "photos of themselves, their partner, friends or pets" onto the subject enum and ties output to "video or photo," and explains the empty-query case for the query parameter. Only limit and season semantics remain implicit.

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 verb and resource ("Find MakeViral trend templates") and immediately explains the resource with concrete examples of what a template is (knight cat, hotel lobby walk, dance reels). It is clearly distinguished from lookup siblings like get_template and list_models.

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 explicit triggers ("user wants a trend video, asks what they can make from a photo, or names a TikTok or Instagram trend") plus the no-argument default behavior. It also hands off to the correct next tool: "use get_template when the user picks one".

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