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

Annotations only declare readOnlyHint and openWorldHint; the description adds substantive context the agent cannot get elsewhere: AIS-derived provenance, a multi-day data lag, an explicit per-call price with payment rails (x402 on Base/Solana/Arc), and the fact that failed calls are free. That is exactly the cost and freshness information needed before invoking a paid tool.

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 dense sentences: purpose and breakdown first, then scope exclusions and latency, then price. Every clause carries information, though the pricing/payment-rail clause is lengthy relative to the rest and could be tightened without loss.

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 one-parameter, read-only, open-world data feed with an output schema, the description covers what the data is, what it is not, how fresh it is, where it comes from, and what it costs. Nothing an agent needs to decide to call it is missing.

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% and the single 'days' parameter (1-30, default 7) is fully documented in the schema. The description implies recency-based querying via 'Daily' and the lag note but adds no range, default, or format details beyond the schema, so the baseline 3 applies.

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+resource (daily vessel transits through the Panama Canal chokepoint) plus the breakdown dimension (ship type) and the source (IMF PortWatch, AIS-derived). It is clearly distinguishable from siblings like logistics_suez_canal_telemetry, logistics_strait_malacca_transits, and logistics_port_congestion_index.

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?

'Covers transit counts only, not booking slots or draft restrictions' explicitly excludes adjacent use cases, and the latency note ('latest date lags real time by several days') tells the agent when the data is unsuitable for real-time needs. It stops short of naming a specific alternative sibling for those excluded questions, so it is not a full 5.

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