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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely new context by stating it knows only ports in the provider's catalogue, which reinforces the closed-world constraint and tells the agent to expect misses outside that catalogue.

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 sentences, no filler. The high-value routing and exclusion information is front-loaded, and the closed-catalogue caveat is placed at the end where it belongs.

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?

With no output schema, the description does the work of naming the returned fields, and annotations cover the safety profile, so an agent knows what it will get. The only omission is behavior when a port is not found in the catalogue or is ambiguous, which is minor for a read-only lookup tool.

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%; the port, handle and language parameters are all documented in the schema, including the handle's continuation semantics and the language enum. The description adds no parameter-level detail beyond that, so the baseline of 3 applies.

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?

States a specific verb+resource ('Returns facts about a cruise port') and enumerates the exact facts returned: country, port code, coordinates, route count. It also distinguishes itself from adjacent content domains (excursions, sights, weather, transfers), so an agent can separate it from siblings like ship_profile or cruise_line_profile.

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?

Gives explicit triggering context ('when the user asks about a port of call or departure port') and a clear when-not list (no excursions, sights, weather, transfer advice). It stops short of naming which sibling tool to use instead for those needs, so it is strong but not fully routing.

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