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 useful non-structural facts: the contents of a saved package and the requirement for a Cotlet API key with access to this app, which the annotations do not convey.

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?

Three sentences that are mostly front-loaded, but the definition repeats itself: sentence one and sentence three both restate that a saved package holds size and weight and may hold extras. That duplication costs it a point.

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 zero-param read-only list tool with annotations covering safety and no output schema, the description covers what is returned and what it is for. It stops short of describing ordering, pagination, or empty-list behavior, but nothing essential to invoking it 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?

The tool takes zero parameters, so the schema has nothing to document and the baseline is 4. The description correctly adds no spurious parameter talk.

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 and resource ('list saved packages') and immediately defines what a saved package contains (size, weight, extras like Signature Confirmation or insurance). It also names the downstream siblings that consume the result (get_rates, create_batch, buy_label), so an agent can place it precisely in the workflow.

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 gives clear context for why you'd call it: the return values are 'presets you can pass to get_rates, create_batch and buy_label'. That effectively signals the use case, but there is no explicit when-not guidance or statement of alternatives if the user wants a filtered or single-package lookup.

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