Ferry timetable

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

Annotations already declare readOnly and open-world, so the safety profile is covered. The description adds genuinely useful context beyond that: live status fields only apply to today, and service alerts such as typhoon suspensions may appear — behavior an agent would not learn from annotations alone.

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 tightly packed sentences: capability first, examples last. Every clause carries information. Slightly dense with the embedded example list, but nothing is wasted.

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, so the description must convey what comes back — and it does (sailing times, today-only live status, service alerts). Combined with fully documented parameters, an agent has enough to call it correctly; only the sibling-routing guidance is thin.

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%, so the baseline is 3. The description reinforces parameter meaning with a worked example (from 富岡 to 綠島, city PenghuCounty), which clarifies how city interacts with port names, but it adds no syntax or constraint detail beyond the 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 gives a specific verb and resource — ferry sailings from one port to another on a given day — and names the return content (times, live status, service alerts). The concrete port examples make the scope unambiguous. It does not, however, distinguish itself from siblings like ferry_live_board or ferry_alerts, which cover overlapping live/alerts territory.

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?

Usage is only implied: an agent can infer this is for planning a crossing on a date. There is no explicit statement of when to choose this over ferry_live_board (today's departures board) or ferry_alerts (dedicated alerts), even though the description mentions both live status and alerts as included features.

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