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

Beyond the destructiveHint annotation, the description explains the financial effects: credit and first top-up bonus leave the balance, the card is credited back with tax, and the service fee is kept. This is exactly the kind of consequence detail an agent needs before invoking a destructive refund operation.

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 front-loaded with the refund action and key constraints, but it is awkwardly phrased and contains a duplicated trailing sentence: 'Free. Free.' That redundancy and the run-on eligibility sentence reduce polish.

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 one-parameter destructive tool with no output schema, the description covers eligibility, default behavior, financial effects, and fee treatment. An agent has enough information to decide whether and how to call it.

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 carry parameter meaning. It does so by explaining that topup_id is optional and that omitting it refunds the newest top-up, with GET /v1/topups as the way to list ids.

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 and resource: refund a top-up. It also specifies the core eligibility condition (paid in the last 24 hours and unused), so the agent can distinguish this from unrelated account and books 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?

It clearly states when the tool applies: a top-up paid in the last 24 hours that has not been used. It also explains the default behavior when topup_id is omitted, though it does not name a sibling alternative or explicitly describe when not to use it.

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