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

Annotations already cover the safety profile (readOnly, non-destructive, openWorld), and the description adds real value on top: newest-first ordering, the fact that batches surface as their labels, and an explicit auth requirement (Cotlet API key with access to this app). That is substantive behavioral context beyond the annotations.

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?

The first sentence front-loads what the tool returns and the remaining sentences efficiently cover ordering, batch handling, follow-up routing, and auth. No filler, though the colon-heavy first clause is slightly dense.

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 no output schema, the description must (and does) describe the returned grid columns and ordering, and it flags the auth prerequisite. It is adequate for a read-only list tool, missing only explicit pagination behavior despite a cursor parameter.

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%, so all five filters (since, cursor, search, status, service) are already documented in the schema, including the 'as the grid filter names it' phrasing. The description adds no parameter syntax or format detail, so baseline 3 is correct.

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?

The description states a specific verb+resource (lists label/shipment purchases) and enumerates the returned fields (recipient, carrier, service, cost, tracking, status), which clearly separates it from single-record tools like get_shipment. It does not, however, contrast against siblings such as pirate-ship_export_shipments or list_import_orders, so sibling differentiation is partial.

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?

It tells the agent what to do with the resulting shipment_id (use with get_shipment or refund_label), which is genuinely useful routing, but it never states when to choose this list over the other Pirate Ship listing/export tools or any exclusion conditions. Usage is implied rather than spelled out.

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