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

Annotations already establish readOnlyHint and idempotentHint, and the description adds useful behavioral content beyond that: results are 'currently inside' at call time and 'newest report first'. It also discloses the anonymous-call area limit of 100 square degrees, which is not present in annotations or schema. No contradiction exists.

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?

Three short sentences each carry distinct value: the core behavior, the intended use cases, and an important constraint. It is front-loaded with the most important information and contains no filler or repetition.

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?

Given annotations, an output schema, and 75% parameter-documentation coverage, the description is largely complete: it explains ordering, areal scope, use context, and a rate/area constraint. It could have added a sentence about pagination or the limit parameter, but the schema already covers those defaults and maximums.

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 coverage is 75%, so most parameter meaning is already available in the schema. The description adds no deeper semantics for the parameters themselves beyond summarizing 'optional kind and ship-type filters', which is lighter than the schema's own examples and constraints. It does not compensate for the remaining 25% of undocumented schema meaning.

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 states a specific verb and resource: 'Vessels currently inside a latitude/longitude bounding box', and adds ordering and filter details. It clearly distinguishes this tool from near-based, name-based, and generic vessel lookups by its bounding-box scope.

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 phrase 'Use for what is in a port, a strait, or a stretch of coast' gives clear context for when this tool is appropriate. It does not explicitly name alternatives or state when not to use it, but the use-case guidance is actionable and the boundary constraint is communicated.

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