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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered at the structured level. The description adds a preview of what results contain (IDs, codes, locations) and does not contradict the annotations. It omits scope (all ports vs. regional), ordering, or pagination, but with a zero-parameter read tool this is a modest gap.

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 front-loaded sentence with no filler. The only minor issue is mild redundancy in the list ('ferry ports, harbors, maritime terminals' are overlapping categories), but it is short, scannable, and every clause contributes meaning.

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 zero-parameter, read-only listing tool with an output schema, the description is essentially complete: it states what is found and what the caller receives. It could note whether the port set is exhaustive or filtered by a region, but nothing an agent needs to invoke it correctly is missing.

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 are 0 parameters, so the baseline is 4 — there is nothing to describe beyond the schema, which is empty. The description usefully signals what the caller can expect back (port IDs, codes, geographic locations), which is the meaningful semantic content for a param-less listing tool.

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 has a specific verb ('Find') and a clear resource class: ferry ports, harbors, and maritime terminals, plus what it returns (port IDs, codes, geographic locations). It is distinct from the siblings, which cover trips, disruptions, and connections. However, it doesn't name or explicitly contrast any sibling, so differentiation is left implicit.

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 context is implied by the resource type — this returns port identifiers that would feed sibling tools like trip or connection lookups — but there is no explicit when-to-use guidance or mention of alternatives. The purpose is self-evident enough that an agent would not misroute it, but no exclusion or priority is stated.

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