congestion

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

With no annotations, the description carries the full behavioral burden and handles it well: it discloses deduplication ('a vessel reporting twenty times in an hour counts once'), the zero-vs-no-coverage ambiguity, and the mechanism for resolving it ('reports how many positions each hour was built from'). This is precisely the kind of non-obvious behavior an agent needs to interpret results.

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 compact, front-loaded with the core purpose, and every sentence adds value—counting semantics, deduplication, and zero-coverage caveat are all meaningful. The charterer analogy is brief and supports usage rather than padding.

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?

The combination of a fully documented schema, an output schema, and strong behavioral caveats makes the tool largely complete for an agent. The only notable gap is the implicit default area behavior when neither bbox nor region is supplied—the schema says 'instead' and lists empty defaults but never states what happens on a no-argument call.

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 already describes all three parameters (bbox, hours, region) at 100% coverage, so the description does not need to restate them. It adds no parameter-specific semantics beyond what the schema provides, so 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?

Opens with 'How busy an area has been, hour by hour' and immediately specifies the mechanism: counts distinct vessels per hour by reporting status (anchored, moored, under way). This makes its scope clear and separates it from siblings like traffic_density, which would focus on density rather than status-split vessel counts.

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 a strong domain cue—'the anchored count is the one that answers "how long is the queue"'—so an agent can infer when congestion is relevant. However, it never names sibling tools or states when to prefer this over traffic_density, anchorages, or vessels_in_area, so the choice is left to inference.

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