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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds that entries include identifiers and that the optional query filters by name/slug, but these largely repeat schema details and do not disclose additional behavioral traits like pagination or edge cases.

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?

The description is two sentences, front-loaded with the verb and purpose, and contains no filler or redundant information.

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 list tool with a rich output schema, thorough annotations, and full parameter documentation, the description adequately conveys its role as a provider of identifiers for the sibling search tools. No gaps remain for the agent to select and invoke the tool correctly.

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 input schema has 100% description coverage for both parameters, including the limit default and query matching semantics. The description restates the query behavior without adding new meaning, so it does not exceed the schema baseline.

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 uses a specific verb 'lists', names the resource 'harbors and destination regions', and emphasizes that entries include identifiers the search tools accept. This clearly distinguishes it from sibling search tools (charter_search, fishing_search, sailing_search) which perform searches rather than list reference data.

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?

The description clearly implies usage as a precursor to searches by stating identifiers are 'the search tools accept.' It provides clear context for when to invoke this tool but does not explicitly state exclusions or name alternative tools, which keeps it just short of a 5.

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