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 covered. The description adds no behavioral detail beyond purpose — nothing about how the recommendation is derived or any caveats. Adequate but adds little beyond the structured 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 tight sentences with the trigger condition front-loaded and zero filler. Every clause earns its 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?

An output schema exists, so return values need not be explained, and one required parameter is fully documented in the schema. What remains thin is how the recommendation is produced or what differentiates it from compare_plans/recommend_plan, but nothing needed to invoke it correctly 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% for the single 'countries' parameter ('Countries on the itinerary'), so the schema carries the parameter semantics. The description only alludes to 'the country list' without adding format or granularity guidance, matching the baseline 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 (recommends) and resource (single-country vs regional vs global plan types) scoped to multi-country itineraries. The multi-country qualifier implicitly separates it from recommend_plan and list_available_plans, but no sibling is named explicitly.

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 opening clause 'Use when the user has a multi-country itinerary and asks which eSIM plan type fits' gives a clear triggering condition. It stops short of naming the alternative to use for single-country itineraries or stating exclusions, so it is context-rich but not fully routing.

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