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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is clear. The description adds a useful scoping detail: it returns only remaining data and status, and only for eSIMs we issued. No additional behavioral detail such as error cases or data freshness is provided, but the annotations lower the burden.

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 concise sentence with no filler. It front-loads the key result ('Remaining data and status') and then adds the scope ('eSIM we issued'). Every word contributes meaningful information.

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?

Given the tool's simplicity, the existing output schema, and the read-only annotations, the description covers the essential context. It could be improved by explicitly stating that the iccid is the lookup key, but that is already evident from the input schema. Overall, the description is sufficient for correct invocation.

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 input schema has 0% description coverage, so the description must compensate. It partially does by clarifying that the iccid must refer to an eSIM we issued. However, it does not explain the iccid format, how to obtain it, or any constraints beyond issuer scope.

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 identifies the resource (an eSIM we issued) and the information returned (remaining data and status). This clearly maps to the tool name get_usage, though it lacks an explicit verb like 'retrieves'. It is not a tautology and is reasonably distinguishable from sibling tools.

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 phrase 'we issued' implies the tool is for eSIMs provided by this system, giving some usage context. However, there is no explicit guidance about when to prefer this over alternatives, nor any mention of excluded cases. Usage is inferable but not directly stated.

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