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

Annotations only cover readOnly/openWorld, and the description adds real value beyond that: AIS-derived provenance, a ~1-week data lag, the fact that it returns counts rather than movements, x402 pricing across three chains, and that failed calls are free. Minor ambiguity between 'with capacity' and 'Transit counts only' slightly blurs what is actually returned.

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 what it returns, then caveats, then the alternative, then pricing – a sensible order. The pricing clause and the long sibling reference are dense but each carries decision-relevant information; only slight trimming would help.

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 shape need not be described, and the description covers source, latency, and cost. It could still say how often the series refreshes within the lag or whether the window is calendar days, but nothing essential to 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 description coverage is 100% and the single 'days' parameter is already documented as 1 to 30 with a default of 7 in the schema. The description adds no further meaning about the window, time zone, or behavior at the bounds, so 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 Suez Canal') plus the breakdown dimensions (ship type categories, capacity) and the upstream source (IMF PortWatch, AIS-derived). It is unmistakably distinct from sibling transit tools such as logistics_strait_malacca_transits or logistics_dardanelles_bosphorus.

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?

Explicitly routes the agent to the sibling logistics_panama_canal_transits for the Panama chokepoint, which is the near-miss alternative. It does not, however, give guidance for the other transit/chokepoint siblings or state exclusions (e.g., when to prefer logistics_vessel_tracker for individual vessels rather than counts).

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