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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds meaningful context beyond annotations: the fallback to catalog popularity and the fact that the response labels which method was used, which helps the agent interpret results correctly.

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 with no filler; the primary behavior and fallback are both stated efficiently. The phrasing 'are adding ... most over the last 30 days' is slightly awkward but does not hurt clarity.

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?

For a simple, optional-parameter, read-only list tool, the description covers the key expectation (trending live data), the fallback, and the response labeling. Without an output schema, a bit more detail about the response shape would help, but the tool is simple enough that this is a minor 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?

There is only one parameter, limit, and the schema fully documents its type, range, and default. The description adds no parameter-specific detail, but no additional meaning is needed given 100% schema coverage.

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 identifies a specific resource (coffees users are adding to collections) and a time window (last 30 days), making the purpose clear. It lacks an explicit verb like 'returns' or 'lists,' but the meaning is unambiguous and distinguishable from generic search or recommendation siblings.

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 description conveys when it applies (trending over 30 days) and includes a fallback condition for when live activity data is unavailable. However, it does not explicitly contrast with alternatives such as search_coffees or get_recommendations, leaving some selection judgment to the agent.

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