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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered structurally. The description adds that results include full specs, prices and a direct link, but discloses nothing about pagination, result limits, or behavior for unknown destinations, so it adds only modest value.

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?

Three short sentences: purpose, return content, and usage trigger, with the primary resource stated first. Nothing is filler, despite the minor awkwardness of the "e-eSIM travel eSIM" phrasing.

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-value detail is unnecessary here, and the annotations cover the safety profile. The remaining gap is sibling disambiguation within a three-tool family where responsibilities are only implied.

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%, so all four parameters (including the enum values and the currency/language handling) are already documented in the schema. The description restates the destination concept (country or region) but adds no syntax or constraint beyond that, matching the baseline for a fully covered schema.

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 names a specific verb and resource ("Find eSIM travel eSIM plans for a destination") and states the return content (specs, prices, direct link). It does not, however, distinguish itself from siblings get_plan_details or start_checkout, leaving overlap between "full specifications" and a details tool.

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?

"Use when a user wants mobile data abroad" gives a clear, actionable usage trigger. There is no when-not guidance and no routing to siblings (e.g., when to call get_plan_details instead), so it stops 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.