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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds one useful behavioral fact — results are limited to currently available destinations — but says nothing about how plans are ranked, whether pricing is included, or what the 'need' tiers mean in practice.

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 short sentences with the core action and the availability caveat front-loaded. No filler or repetition of the title.

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 needn't be explained, and annotations cover safety. Still, for a search tool where 'need' silently shapes results and 'days' is a required input with a hard cap, the absence of any explanation of those inputs leaves the description under-complete for correct invocation.

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 0%, so the description must carry the load. It clarifies destination formats (country name, ISO code, or region), which the schema does not, but leaves 'days' (1–90 night range) and especially 'need' (light/standard/heavy) completely unexplained, so two of three parameters remain opaque.

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 and resource (find travel eSIM plans) and names the acceptable destination formats, which is more than the schema says. It does not, however, distinguish itself from siblings like list_destinations or get_checkout_link, so an agent must infer the boundary.

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?

There is no explicit when-to-use or when-not-to-use guidance and no mention of the alternatives (list_destinations, get_checkout_link). The only implicit signal is that this is the search step before checkout, which the agent has to reconstruct from sibling names.

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