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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so the safety profile needs no restating. The description's 'No Viator product request' adds genuine context about the absence of an external product call, consistent with openWorldHint=false, and it discloses what the result contains beyond a bare ID list.

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?

Three short sentences, front-loaded with the resource and purpose before the follow-up instruction. Nothing is padded or restated from the title or annotations.

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 parameters and no output schema, the description must carry the return-value information itself, and it does: ports with a supported/unsupported flag plus the ID to use downstream. For a trivial lookup tool this leaves no meaningful gap.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate, and the 100% coverage baseline applies. The description does not need to explain inputs and correctly spends its words on output and follow-up instead.

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 and resource ('List local cruise ports') plus the flag it returns ('whether excursion searches are supported'), and adds a scoping note ('No Viator product request'). It is clearly distinguishable from the excursion-search siblings, though it does not differentiate itself from other list_* tools such as list_departures.

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?

Explicitly routes the agent forward: 'Use the returned port ID for find_port_excursions' tells the caller this is a prerequisite lookup step rather than the search itself. No when-not-to-use condition is given, but the intended sequence is unambiguous.

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