port_calls

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

With no annotations, the description carries the full burden, and it excels: it discloses that only observed events are reported, that missing departures are not assumed, that stops are cut at coverage holes, and that arrival_observed is false when arrival was not witnessed. This is exactly the kind of data-provenance and assumption-avoidance context an agent needs.

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 moderately long but every sentence earns its place: a punchy first sentence, a clarifying analogy, a laytime distinction, then precise caveats about observation and coverage. It is front-loaded with the core purpose and structured so the most important behavioral rules come last.

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 tool with an output schema and fully documented parameters, the description is remarkably complete. It explains the meaning of key output concepts (arrival_observed, no assumed departure, at-sea stops) and the reasoning behind anchored vs moored distinctions. Nothing an agent needs to interpret results 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?

Schema description coverage is 100%, so the parameters are already well documented. The description adds meaningful context about output semantics but no additional meaning for the query or days parameters themselves. Therefore the baseline score of 3 is appropriate.

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 opening sentence clearly states what the tool reports: when a vessel stopped, where, for how long, and whether she was working. It describes a distinct resource (recorded port calls) and adds useful framing as the skeleton of a Statement of Facts. However, it does not explicitly differentiate itself from siblings like vessel_track or passage_time.

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 gives clear contextual triggers: this is the tool for observed stop-level facts (arrival, time alongside/at anchor, departure) and distinguishes waiting vs working in laytime terms. It does not name alternative tools or exclusions, but the use case is evident enough that an agent would not confuse it with a live tracking tool.

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