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

Annotations already establish the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower, and the description adds genuinely useful context beyond them: satellite-AIS sourcing, free/no-key upstream, and a paid x402/Base access model at $0.03. It does not describe latency or rate limits, but the payment and provenance details are substantive additions.

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?

Front-loaded with the core capability, but it carries marketing framing ('leads official macro data by weeks') and states the x402 cost twice (prose plus a trailing bracket), which is redundant. Dense but with a couple of sentences that don't fully earn their place.

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?

For a no-output-schema, one-parameter tool, the description covers coverage set, metrics, cadence, source, and access cost — enough to call it correctly. Missing only finer return-format details, which is a minor gap given the absence of an output schema.

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 100% but the single parameter's schema description is merely a truncated paste of the tool blurb, so it contributes little. The description compensates by naming concrete preset values (Shanghai, Singapore, Rotterdam, LA, Long Beach) and indicating any port name is accepted, which adds real input semantics.

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 — daily port activity across 2,065 named ports — and enumerates the metrics returned (port calls, estimated dwt, 7d vs 30d deviation, anomaly flag). This is clearly distinguishable from macro siblings like ecb_macro or volume_anomaly without opening any schema.

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?

Explains the use case well: port volume as a leading indicator for trade/tariff/recession markets, plus the data source (IMF PortWatch) and frequency. However, it never routes the agent away from or toward a specific alternative among the many macro/econ siblings, so it stops short of explicit when-not guidance.

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