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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely non-structured information: results are ranked by count of matching sights and each recommendation is accompanied by a rationale, which tells the agent what kind of output to expect beyond the hints.

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 compact sentences: purpose first, then examples, then ranking behavior. Every clause earns its place and the actionable content is front-loaded.

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 five optional parameters and no output schema, the definition covers what an agent needs: what the tool returns conceptually and why results are ordered as they are. It stops short of stating behavior for an empty-criteria call or default-ranking fallback, a minor but real gap for an all-optional-parameter tool.

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 80%, including enum value lists and per-field notes, so the schema does most of the work. The description reinforces the interests/periods duality and that matching sight counts drive ranking, but adds no format or interaction detail (e.g. how country interacts with periods, or what happens with zero criteria).

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 ('Suggest covered European cities') plus the scope constraint ('covered', i.e. catalog cities) and the ranking logic. The two example queries make the intended input shape concrete and distinguish it from search_cities or recommend_attractions without ambiguity.

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?

Clear context for when to use it: open-ended, interest- or period-driven city suggestions, illustrated with two example phrasings. It never names an alternative or an exclusion (e.g. use search_cities for a known city name), so it falls short of explicit when-not guidance.

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