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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description nonetheless adds useful context beyond the annotations: the exact shape of the return (packages each with package_id and lowest price) and the auth prerequisite ('Cotlet API key with access to this app').

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 return contents are stated twice — first as 'Packages with prices, what is included, meeting point and cancellation policy' and again as 'It also returns what is included, the meeting point and the cancellation policy.' That redundancy wastes a sentence, though the tool-routing and auth notes earn their place.

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 correctly carries the burden of describing return values, and it does so in detail. Combined with the auth note and the downstream tool linkage, an agent has almost everything needed; only explicit exclusion guidance 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% and the single parameter is documented as 'Activity ID from search_activities.' The description adds no syntax, format, or sourcing detail beyond what the schema already provides, so the baseline of 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 pair (fetch one activity) and richly qualifies scope: 'one activity with its packages', plus included items, meeting point and cancellation policy. It names sibling tools (check_availability, book_activity) but as downstream consumers rather than as alternatives, and the opening 'Klook: Packages with prices...' delays the verb slightly.

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 clear workflow context: 'Use package_id with check_availability and book_activity', which tells the agent this is the pre-booking detail step. It does not explicitly state when NOT to use it or contrast it with search_activities, but the role in the flow is unambiguous.

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