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

Annotations already declare readOnly, idempotent, non-destructive, closed-world. The description adds genuine behavioral context beyond them: ranking is by visitation, each result carries the figure its month was decided on, cloud is deliberately excluded for northern-lights, and places under travel advice are never listed. That last constraint is a real inclusion rule not present in structured data.

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 content is dense and largely earned, but it is delivered as one sprawling sentence-chain with parentheticals that is hard to parse. Front-loading is weak; the core behavior (month vs no-month) is buried mid-paragraph rather than stated up front.

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 does the work of explaining what is returned (ranked places with the deciding figure, plus rules and sources). Combined with the annotations covering safety, this is nearly complete; only explicit sibling routing is missing.

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 coverage is 100% so the baseline is 3, and the description exceeds it: it elaborates what each activity enum value means (dry days of 10–27 °C, warm calm sea, deep snow with running lifts), clarifies that an absent month yields per-month counts, and confirms limit selects the most-visited first.

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 states a specific function: ranking places by whether a given activity's month is good or fair, with rankings by visitation. It defines the four activities and their criteria clearly. It does not name or contrast with siblings like best_months or where_to_go, so it is clear but not sibling-differentiated.

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?

Usage is implied rather than stated: with a month you get ranked places, without it you get per-month counts. There is no explicit when-to-use or when-not-to-use guidance versus alternatives such as best_months or where_to_go, which an agent would need to disambiguate.

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