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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so safety is covered. The description adds real value beyond that: it discloses that later plan calls carry a purchase_url and that comparison output is not a personal recommendation or policy — useful framing for an agent handling user-facing advice.

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?

Four short sentences, with the operation front-loaded and the prerequisite immediately after. The disclaimer sentence is somewhat boilerplate but does carry compliance value, so nothing is clearly wasted.

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 input parameters and no output schema, the description carries the burden of describing the response — and it does so by naming the five categories of values returned. It stops short of saying how the values are structured (grouped vs flat), which is the only remaining 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?

The tool takes zero parameters, so the baseline is 4; there is nothing the description needs to disambiguate. The enumerated return categories effectively serve as the parameter vocabulary the agent will later use with sibling tools.

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 uses a specific verb ('List') and enumerates exactly what is returned: destinations, insurers, feature filters, score floors, sort orders. This clearly marks it as a vocabulary/metadata tool distinct from list_travel_plans, though the relationship to get_travel_plan is left unaddressed.

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?

'Call this before list_travel_plans' gives an explicit ordering and prerequisite, and the purchase_url sentence clarifies downstream context. There is no stated 'when-not' or exclusion, which keeps it just short of a 5.

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