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

No annotations are present, so the description carries the full burden of behavioral disclosure. It does note the operation is read-only and describes the required credentials, which adds some transparency. However, it does not mention failure modes, rate limits, or the format of the returned OTP/code, so the transparency is limited.

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 English portion is well-structured: it states the purpose, prerequisites, when-to-use, and alternatives in compact sentences. The score is not 5 because the Vietnamese translation is largely redundant, doubling the description length for the same content.

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 is simple and its two parameters are fully covered by the schema. The description covers prerequisites, use case, and alternatives, which is strong for a read-only lookup tool. However, it does not discuss the output or how OTP retrieval behaves (e.g., live polling vs cached), leaving some ambiguity for the agent.

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 schema already documents both required parameters. The description reinforces that order_code must be for a mail-bundled account, which adds a small nuance beyond the schema, but it does not compensate for low schema coverage or add deep value. Baseline 3 is appropriate.

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 verb 'get' and the specific resource ('latest email OTP / verification code' for a mail-bundled account), and explicitly distinguishes the supported providers. It also helps differentiate from sibling tools like get_2fa and check_order_status.

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 provides a clear PREREQUISITE (api_key + order_code with inbox), a WHEN TO USE statement, and explicit PREFER INSTEAD alternatives (get_2fa for TOTP, check_order_status for delivered credentials). This fully covers when and when not to use the tool.

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