topup_esim

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

No annotations are provided, so the description must disclose behavioral traits. It mentions the prerequisite 'active eSIM' but omits critical details for a purchase operation: financial implications, error behavior on invalid product ID or inactive eSIM, idempotency, and side effects. This is a significant gap for a tool that likely charges money.

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 sentence with a clear conditional structure, front-loaded with the main action. No wasted words; every clause earns its place.

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?

The tool has no output schema and no annotations. The description covers both modes and the prerequisite but omits financial consequences, error cases, and return data. Given that this is a purchase tool, the missing context is notable, though the core behavior is sufficiently outlined.

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 0%, so the description must compensate. It explains that topup_product_id toggles between browse and purchase, and implies esim_id targets the active eSIM. This adds meaning beyond the raw schema, though esim_id semantics remain implicit.

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 clearly states a dual purpose: browsing top-up products or purchasing a specific top-up, with the distinction based on the presence of topup_product_id. It specifies the resource (active eSIM) and differentiates from purchasing a new eSIM.

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 gives explicit guidance on when to include topup_product_id (browse vs purchase), and implies use case for active eSIMs. It does not explicitly exclude alternatives but the context is clear enough for an agent to select this tool over purchase_esim or other siblings.

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