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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description does add genuine context beyond them: the upstream data source (IMF PortWatch) and the exact comparison basis (latest day against a 30-day average). It says nothing about update cadence, delay, or what the numbers represent numerically (transit counts vs. an index).

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?

Two tight sentences that lead with the data source and scope and close with the interpretive caveat. Every clause carries information: source, geography, metric, baseline window.

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 and no parameters, the description gives enough to know what comes back conceptually (per-chokepoint latest day vs 30-day average). It leaves the update frequency and whether values are counts or normalized indices unstated, which matters for a time-sensitive indicator.

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 tool takes zero parameters, so the baseline of 4 applies; there is no parameter meaning to explain. The description correctly implies a fixed, no-argument call reporting all five chokepoints.

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 the concrete resource (IMF PortWatch daily vessel transits at five named chokepoints) and the exact metric (latest day vs 30-day average), which is far more specific than a bare name restatement. It stops short of explicitly distinguishing itself from the sibling get_chokepoints or get_hormuz, so an agent must infer the difference.

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?

There is no statement of when to call this versus get_chokepoints, get_hormuz, or get_geo, and no prerequisites or exclusions. 'Indicator, not advice' is a caveat about interpretation, not guidance about tool selection or invocation timing.

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