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

Annotations already indicate this is a non-read-only, non-idempotent operation. The description adds the return behavior (VietQR code) and package details, but it does not disclose that the account is likely credited only after payment is completed, nor the side effects of creating multiple orders. No contradiction with annotations, but the behavioral picture is incomplete.

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 compact and front-loaded with the core purpose and output. The second sentence adds package-format and promotion details that help in choosing the plan parameter, though it is slightly more marketing-like than strictly necessary.

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?

There is no output schema, so the description needs to explain the return value; it does mention the VietQR code, but it omits details such as whether an order ID is returned and how to check order status afterward. For a tool with only one parameter, this is mostly adequate but leaves notable gaps around the payment flow.

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 coverage is 100% and the enum values are already documented, so the baseline is 3. The description adds value by explaining the package format (<tier>-<duration>), the pricing tradeoff per month, and the extra .com domain bonus for certain 12-month plans, which helps the agent choose a correct plan value.

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 uses a specific verb and resource ('Nạp tiền vào tài khoản' – top-up the account) and clearly states the key output ('trả mã QR VietQR'). This makes it easy to distinguish from siblings like create_vps and get_order_status without naming them explicitly.

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 clear context for when to use the tool: when the goal is to recharge the account and receive a VietQR payment code. It does not explicitly mention exclusions or alternative tools, so it stops short of a 5, but the intended use is unambiguous.

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