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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds only the vague notion of 'best plan(s)', implying ranked results, but discloses nothing about ranking criteria, how many plans return, or what happens when no plan fits.

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?

A single, front-loaded sentence that names the action, the resource, and the qualifying inputs with zero filler. Nothing is wasted or buried.

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?

For a read-only recommendation tool with no output schema, the description covers the required inputs adequately but omits what the recommendation actually returns (list of plans with prices?) and how 'light/medium/heavy' map to data allowances. Adequate but with clear gaps.

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 only 25%, so the description must compensate. It does explain tripDays and usage (light/medium/heavy as expected data usage), which maps the required inputs, but it says nothing about destination format (country/region code?) or the locale parameter's dual role of language and currency. Partial compensation, hence 3.

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 (Recommend) and resource (best plan(s)) plus the three inputs that drive it (destination, trip length, usage level). It is clearly a recommendation tool rather than a raw lookup, which helps distinguish it from search_plans/get_plan. It stops short of explicitly naming those siblings, so it doesn't fully earn a 5.

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?

The trip-planning framing implies when to call it, but there is no explicit when-to-use vs. when-not, and no mention of the very close sibling search_plans. An agent must infer that this is the higher-level 'advise me' entry point versus the lower-level search/list tools.

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