List Ferry Ports

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint, so the safety profile is fully covered. The description adds useful behavioral context by revealing that results are limited to two specific operators (all their ports), which is knowledge the agent cannot get from annotations. It does not disclose result size, ordering, or what a port record contains.

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 sentence that leads with the resource and then the scope; no filler, no repetition of the title.

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 simple read-only listing tool this is close to adequate, and the operator scope is stated. However, with no output schema, the description should say what a port entry includes (name, operator, ID) and what the default language is; neither is covered.

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?

There is a single optional 'language' parameter with an enum (ja/en/zh) and 0% schema description coverage. The enum values are largely self-explanatory, but the description never mentions that output language is selectable or what the default is, so it adds nothing 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+resource ('フェリー／水上バス港一覧' / displays all ports) and narrows scope to two named operators, Tokai Kisen and Tokyo Cruise. That scope statement distinguishes it from route-searching siblings like search_ferry and get_operator_routes, though it does not explicitly contrast with list_transit_operators or get_station_info.

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?

It never states when to call this versus alternatives such as search_ferry, get_operator_routes, or list_transit_operators. The only implicit cue is that it is a full listing restricted to two operators; no exclusions or prerequisites are given.

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