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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds nothing beyond them: it does not say whether matching is exact or fuzzy, whether partial strings are allowed, or whether multiple labels can be returned — a meaningful ambiguity for a lookup tool.

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 front-loaded sentence with no filler, which is appropriately sized for a simple lookup. It is arguably too terse, since the same brevity that keeps it clean also leaves the routing question unanswered.

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?

There is no output schema, and the description does not state that this returns a list bounded by the limit parameter (default 10), nor what happens when nothing matches. For a tool in a namespace with four or five near-duplicate lookup siblings, this is not enough to call it correctly.

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 both 'query' and 'limit' are documented in the schema and the baseline of 3 applies. The description restates the query keys but does not add matching semantics or explain how 'query' auto-detects between track & trace, label id, reference and usage id.

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 gives a specific verb (Find) and resource (shipping labels) plus the four lookup keys, which is more than a restated title. However, it never distinguishes itself from close siblings such as GetLabel, SearchShippingLabels, LookupByTrackTrace and ListRecentLabels, all of which appear to operate on the same resource.

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 FindLabel versus SearchShippingLabels, GetLabel or LookupByTrackTrace, which are the obvious alternatives in a crowded label namespace. The agent is left to infer that this is a general-purpose lookup rather than a narrower one.

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