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

With no annotations, the description carries the full behavioral burden; it discloses the covered countries and subject domains, which helps the agent know what it will get. However it says nothing about return format, whether the answer is static or live, currency of regulations, or any usage constraints. Adequate but with gaps.

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 dense sentence with the subject front-loaded after the bracketed tag. Every listed item is informative, though the '［出國與國旅實用查詢］' prefix is filler that does not earn 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?

There is no output schema and no annotation coverage, so the description should arguably explain what is returned and whether country is optional. It covers scope well but leaves the response shape and requiredness of the parameter unaddressed.

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 coverage is 100% and the single 'country' param already lists 日本／韓國／越南, so the schema does the heavy lifting. The description repeats the same country set without adding format, spelling, or validation details beyond it, so baseline 3 is appropriate.

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 resource (Taiwan passport entry requirements for Japan, Korea, Vietnam) and enumerates the topics covered (visa-free days, Visit Japan Web, K-ETA, e-visa, Phu Quoc). This clearly distinguishes it from siblings like trip__japan_taxfree_rules or trip__destination_info. The noisy bracketed prefix adds no informational value but doesn't obscure the purpose.

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?

Scope is implied by the country list and topic enumeration (entry-based questions for these three destinations), but there is no explicit when-to-use statement and no mention of alternatives such as trip__destination_info. An agent can infer the trigger but receives no routing guidance.

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