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

Annotations only declare readOnlyHint and openWorldHint; the description adds genuinely useful behavior: a 30-minute freshness/rate cap, an attribution obligation under CC BY 4.0, a scope exclusion on ship positions, and that no points are spent. It stops short of saying what happens on a too-frequent call (error vs. cached response), which is the one behavior an agent most needs to handle.

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?

Purpose is front-loaded in the first sentence and the remaining sentences are short and each carry a constraint. The licensing sentence includes provenance clutter ('Their page, read on 2026-11-08') that could be trimmed while keeping the attribution requirement.

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 parameters and no output schema, the description is the only source of information about the return value, and it says only '24-hour summary counts' without indicating what is counted. Constraints and licensing are well covered, but an agent cannot predict the shape of the payload it receives.

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?

Zero parameters, so there is nothing to document and the baseline applies. The explicit note that it 'does not accept a URL' usefully preempts an agent trying to pass one to a no-arg tool.

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?

States a specific verb and resource: 'Read the 24-hour summary counts from the Strait of Hormuz Ship Monitor.' It also delimits scope ('Individual ship positions are not copied'), which separates it from a positions/transit feed an agent might otherwise assume.

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?

Gives operational constraints that shape when the call will succeed (one fresh summary per 30 minutes) and rules out passing a URL, but never names an alternative hub tool or states the condition under which an agent should prefer this over a sibling. Usage is implied rather than routed.

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