Get aggregate vessel counts

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

With no annotations, the description carries the behavioral disclosure burden. It indicates the tool is read-only (aggregate counts) and public (no auth scaffold), but it does not disclose the output format or any limitations. The plural 'counts' hints at a structured return, yet the exact shape is absent.

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 that clearly states the tool's purpose and intended use. No superfluous information; every word earns its place.

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 tool without an output schema, the description should specify what the return value looks like. It says 'aggregate public vessel counts' but does not detail whether it returns a single number, a breakdown by category, or a summary object. This gap could lead an agent to misinterpret the response.

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 zero parameters, so the schema is trivially 100% covered. The description adds no parameter-specific meaning, but none is needed. The baseline for zero-parameter tools is 4, and this description stays within that.

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 clearly states a specific action ('Aggregate public vessel counts') and its intended query type ('how many vessels' questions). The title reinforces the purpose. While it does not explicitly name sibling tools, the aggregate-count nature distinguishes it from lookup_vessel (single record), search_vessel_registries (general search), and get_dataset_metadata (metadata retrieval).

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 clear context for when to use the tool: when the user asks about aggregate vessel counts or quantity questions. However, it gives no explicit guidance on when not to use it or alternatives to consider, leaving that to inference.

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