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

With no annotations, the description carries the full burden. It adds useful scope information not present in the schema (the data is specific to Taiwan passport holders) but says nothing about data currency, whether results are static, or any access/authorization constraints.

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 enumerates the covered topics compactly. Dense but no wasted clauses; the scope is stated first.

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 one-parameter lookup tool with full schema coverage and no output schema, the description adequately conveys the information domain. It is missing any behavioral context (data freshness, applicability caveats), so it is minimally sufficient rather than complete.

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% and the single country parameter is documented in the schema ('日本／韓國／越南'), so the schema already does the work. The description adds no syntax or format detail beyond echoing the covered countries.

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 states a specific resource (entry requirements for a Taiwan passport holder) and enumerates the exact subtopics covered (visa-free days, Visit Japan Web, K-ETA, e-visa, Phu Quoc). This makes it distinguishable from siblings like destination_info or japan_taxfree_rules, though it never names those siblings directly.

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 guidance, no conditions or exclusions, and no mention of alternatives such as destination_info. Usage must be inferred from the topic list alone.

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