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

The annotations already declare this a read-only, open-world, non-destructive operation, so the safety profile is covered. The description adds the 5-degree size ceiling and the shape of the returned fields, which is useful context. However, it leaves the odd idempotentHint=false unexplained for what is ostensibly a pure query, and says nothing about rate limits, result caps, or units of speed/course.

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 with zero filler. The scope constraint and the returned fields are both delivered immediately, and nothing is repeated from the schema or annotations.

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?

With no output schema, the description carries the return-value burden, and naming the four fields helps. But it is thin for a geospatial query: no coordinate conventions, no note on result volume or truncation when the box is dense with traffic, and no mention of the AIS data source's freshness. Adequate, not complete.

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 0%: south, west, north, east are bare numbers with no units, ordering, or antimeridian guidance. The description only partially compensates, conveying that the four values form a box with a 5-degree total span, but nothing about degrees-vs-decimal conventions, coordinate order, or behavior when west > east. For an all-undocumented 4-parameter tool, the description should do more.

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 names a concrete resource (AIS ship reports) and a concrete scope (a bounding box), so an agent knows it returns vessel positions rather than, say, flights or weather. It also lists the returned fields (name, destination, speed, course), which sharpens the picture of what the tool produces. It does not differentiate itself from similar siblings such as cell_sensor_ais_fi or ship_quote, which keeps it out of 5 territory.

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?

"Inside a box of up to 5 degrees" is a real usage constraint that tells the agent how to size the query, which is more than nothing. But there is no explicit statement of when to prefer this tool over the Finnish AIS sibling or ship_quote, nor any warning about what happens if a larger box is requested.

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