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

Annotations already declare the tool as readOnlyHint, idempotent, and non-destructive, so the description does not need to repeat safety traits. It adds useful context by noting the inspection trail appears only after the parcel arrives and that a restocking fee may or may not exist, but it does not describe error behavior or authorization requirements.

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 description is a single, front-loaded sentence that efficiently conveys the operation, its scope, and the notable fields included. Every clause adds relevant information without repetition or filler.

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 low-complexity single-parameter read tool, the description is largely complete: it identifies the resource, how it is selected, and what data the response contains. It could be slightly stronger by noting what happens for an unknown or inaccessible return_id, but this is minor given the schema and safety annotations.

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 schema already documents return_id as 'UUID of the return to fetch' with 100% coverage. The description adds no additional parameter-level semantics beyond the fact that the return is fetched by id, which is already evident.

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 ('Fetch'), a specific resource ('a single return by id'), and the key data returned (reason, status, restocking fee, refund ledger, inspection trail). This clearly distinguishes it from list-oriented tools like returns_list and from label-specific returns_get_label.

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?

The description clearly signals this is the tool to use when a single return's full detail is needed by return_id. It does not explicitly list alternatives or exclusions, but the 'single return by id' phrasing provides clear usage context against the sibling set.

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