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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), and the description adds substantial behavior beyond them: the urgency ordering, the 45-day discharge filter, the meaning of `terms_unknown` as absent carrier free-time terms, and the `collect_by` derivation rule and how to lead with it over the last free day. That is exactly the kind of domain interpretation structured fields cannot carry.

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 risk condition and sort order, then usage examples, then field guidance — a sensible ordering with little waste. It is dense, and the presentation instruction about linking the container number to `shipment_url` and never fabricating URLs edges toward output formatting rather than tool semantics, but it is short and actionable.

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?

No output schema exists, so the description must carry the return contract, and it does: each entry has demurrage and detention clocks with days left and the active clock, plus `collect_by` and `shipment_url`. Given a zero-parameter list tool, an agent has everything needed to call it and interpret the results.

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 arguments, so the baseline is 4 and there is no parameter meaning to add; "Takes no arguments" confirms the empty schema rather than leaving the agent to infer it. The remainder of the description appropriately redirects effort to interpreting output fields instead.

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 and condition: ocean shipments whose demurrage or detention free time is running out or over, sorted most urgent first and limited to those discharged in the last 45 days. An agent can immediately tell this apart from a general `search_shipments` sweep because the risk condition and the 45-day discharge window are named up front.

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?

Gives concrete triggering questions — "what will cost us demurrage this week" and "which containers should we pick up first" — which is stronger than a generic when-to-use clause. It stops short of naming a sibling alternative or an explicit when-not-to-use, so the routing signal is clear but not exhaustive.

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