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

With no annotations and no parameters, the description provides a modest explanation: 'Find ferry ports' indicates a read-only retrieval, and the content categories (ports, IDs, codes, locations) hint at the return data. It doesn't mention scale, formatting, or limitations, but for a simple 0-parameter list tool the disclosure is acceptable.

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 one concise sentence that starts with the primary action, 'Find ferry ports'. It avoids fluff. The long list of data types is slightly dense, but every item contributes to clarifying the tool's purpose.

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 no-parameter tool with no output schema, this description is fairly complete: it tells the agent what kind of data will be returned. It could mention that this is a full list, but given zero parameters, the scope is reasonably predictable.

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 zero properties, so there are no parameters to document. The description still neither ensures but there is no conflict. The 0-parameter baseline of 4 applies because no paraminfo is needed.

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 opens with the actionable verb 'Find' and identifies the resource as 'ferry ports, harbors, maritime terminals, port IDs, codes, and geographic locations.' This is specific enough to distinguish it from sibling ferryhopper tools that relate to trips, disruptions, or direct connections, though it doesn't explicitly contrast with those siblings.

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 provides no guidance on when to use this tool versus alternatives such as airplane... Sorry, there is no mention of how this relates to ferryhopper_get_direct_connections_for_ports or search_trips. It does not mention when the tool should be called first or what workflow it supports, so an agent is left to infer from the name.

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