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

No annotations are supplied, so the description carries the full burden. It discloses that data is live/current ('目前位置與誤點', '即時看板') and that the two modes are mutually exclusive, which is genuinely useful. However, it says nothing about data freshness, update frequency, behavior for non-running trains, or error conditions.

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 tight sentences, front-loading the purpose before the argument constraint, with no filler. The full bilingual duplication is mildly redundant but reasonable for a bilingual audience.

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 two-mode live-query tool with no output schema and no annotations, the description sketches what each mode returns (position/delay vs board) but not the shape or fields of the response. An agent can select the tool but has limited expectations about returned data.

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 compensate, and it does add the critical mutual-exclusivity rule ('恰填一項') that the schema does not express. It still omits format expectations: whether train_no is numeric or with a suffix, and whether station takes a Chinese name, English name, or station code.

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 in both languages: querying the current position and delay of a TRA train, or a station's live board. That implicitly separates it from the timetable sibling (static schedule vs live status), though it never names tra_timetable explicitly.

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?

The constraint 'provide exactly one argument' implies two distinct usage modes (train lookup vs station board), but there is no explicit when-to-use guidance or a named alternative such as tra_timetable for schedule queries. The agent must infer which mode applies from the parameter it supplies.

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