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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered by structured fields. The description adds nothing behavioral beyond that — no mention of link expiry, file format options (PDF/ZPL), max batch size, or whether an empty result is possible.

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?

A single efficient sentence with no padding, and the two selection modes are stated up front. It is slightly under-specified rather than bloated, but nothing in it is wasted.

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 two-parameter tool with no output schema, the description should at minimum resolve the batch_id/shipment_ids exclusivity and sketch what the returned link looks like. Neither is provided, and there is no mention of format or validity window, so an agent could easily call it with no arguments at all.

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 50%: batch_id is documented in the schema, and the description's 'of chosen shipments' implicitly explains shipment_ids. However, with zero required parameters and two mutually substitutable inputs, the description never states that one of the two must be supplied or whether both may be combined — the single most important semantic for this tool.

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 names the resource (printable labels) and the output (a download link), and scopes it to a batch or chosen shipments, which is enough to know what the call yields. It is written as a noun phrase rather than a verb+resource and makes no attempt to distinguish itself from nearby tools like get_label_settings or list_return_labels.

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?

There is no statement of when to use this tool versus its many siblings, no prerequisite (e.g., labels must already be purchased/generated), and no guidance on when to pick the batch path versus the shipments path. The agent must infer all of this from the one-line description.

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