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

No annotations are provided, so the description carries the full disclosure burden. It hints that the tool both computes an estimate and returns setup instructions (iPhone compatibility, EID, SMS on a Taiwan number), which is some behavioral signal. But it says nothing about what the estimate is based on, what the response contains, or how the three inputs influence the result.

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 compact sentence that front-loads the core purpose. No padding or repetition. It is short to the point of under-specification, but that is a completeness issue rather than a structural one.

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?

Three parameters at 0% schema coverage, no annotations, and no output schema mean the description is the only source of guidance — and it omits all parameter meaning and return-value expectations. For a tool whose output an agent must present, this is insufficient.

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% and the description never mentions days, usage levels (light/normal/heavy), or hotspot_people. The parenthetical topics (EID, SMS) do not map to any input parameter, so the description does not compensate for the undocumented schema at all.

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 task (估算出國 eSIM 流量) plus a secondary function (設定說明), which is enough for an agent to know this tool produces an eSIM data estimate. The parenthetical lists the sub-topics covered (iPhone 支援機型、EID、臺灣門號收簡訊), clarifying scope. It is unique among siblings, so no differentiation is required.

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 statement of when to use this tool versus anything else, nor any prerequisite (e.g. trip duration known, destination country). The '出國' qualifier only weakly implies the travel context. Nothing tells the agent when this is the right call.

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