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

Annotations already declare readOnlyHint/openWorldHint/destructiveHint, so safety is covered. Beyond that the description adds real behavioral context: result ordering (most first), exact row fields, and precise definitions of 'stays' (live public listings) vs 'bookableNow' (currently listed for booking). It does not state pagination or result-size limits.

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 the core behavior, then row fields, then usage examples. Every sentence carries information; the example question list is slightly verbose but justified for routing 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?

Despite no output schema, the description enumerates the returned columns and defines both metrics, so an agent knows exactly what it gets back. Combined with a single optional parameter fully covered by the schema, nothing needed for correct invocation 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 description coverage is 100%, so the continent parameter is already documented. The description reinforces it as optional and implies the filter applies per country, but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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+resource+aggregation ('how many stays ... in each country') and ordering ('most first'), clearly distinguishing it from the listing sibling getStaysByCountry. An agent can tell this is a count/aggregation tool without opening the schema.

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 concrete example questions ('which countries have the most stays', 'how many stays do you have in Spain') that anchor when to use it, plus the optional continent filter condition. It does not explicitly name the alternative (e.g., getStaysByCountry for listing actual stays), so it stops short of full routing guidance.

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