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

Goes well beyond the readOnlyHint/openWorldHint annotations by disclosing data staleness (April 2021 cutoff), absence of live queue data, and precise cost behavior ($0.002 USDC per successful call via x402 on Base/Solana/Arc, failed calls free). These are exactly the facts an agent needs before paying for a call.

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?

Three sentences, front-loaded with what the tool returns, then the staleness caveat, then pricing. Every sentence carries distinct value; the payment sentence is long but conveys necessary cost detail.

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 an output schema present, return values need not be explained, and the description covers the remaining essentials: data source, temporal coverage limit, absence of live data, and payment terms. Nothing critical for a correct call 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 is fully documented with range and default in the schema. The description adds no extra meaning about the parameter, 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 resource (Suez Canal) and specific measures (daily transit counts, dwell/idle times) plus derivation method (AIS) and dataset provenance (ADB on HDX). The canal name alone disambiguates it from siblings such as logistics_panama_canal_transits or logistics_strait_malacca_transits.

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?

Provides a clear when-not-to-use caveat: the source ends April 2021 and there is no live convoy queue, which steers agents away from expecting current traffic status. It does not name an alternative sibling (e.g., a live vessel tracker) for live-data needs, which keeps it below a 5.

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