Renew subscription

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

Annotations already indicate non-read-only and non-destructive behavior. The description adds valuable context: a renewal order is placed, and if no payment method is provided, the default one is used automatically. This is meaningful side-effect information beyond the annotations, though it doesn't detail charge timing or impact on the existing subscription term.

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 short and front-loads the main purpose. The phrase 'leveraging the existing billing infrastructure' is mild filler, but it doesn't hurt clarity or distract from the key instructions.

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 3-parameter tool with no output schema, the description covers the operation, the prerequisite lookup for subscriptionId, default payment behavior, and scope. It doesn't mention response format or error conditions, but those are not essential 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?

Schema description coverage is 100%, so the baseline is 3. The description adds some guidance on where to find subscriptionId and repeats the default payment method behavior, but it does not add meaning for the coupons parameter beyond the schema's own description.

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 the operation ('Create a renewal order') and the resource ('existing Hostinger subscription'), and specifies single-subscription scope. It doesn't explicitly distinguish this from related billing siblings like billing_createPurchaseOrderV1 or auto-renewal tools, so it lacks full sibling differentiation.

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 explicitly tells the agent to use the subscriptions endpoint to find available subscriptionId values, and says to use this endpoint to renew any available subscription. It doesn't state when not to use it or name alternatives, but the context is clear enough for correct selection.

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