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

With no annotations provided, the description carries the full behavioral burden. It discloses that the tool is read-only, needs no account, and reveals an important edge case: the deposit address has a network minimum, making inexpensive plans payable annually rather than monthly. This is meaningful behavior beyond the schema.

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?

Front-loaded with the most important facts: pricing, plan scope, currency, and billing intervals. It is compact, but the Korean section duplicates the English content and adds length without new information for an English-language agent.

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, read-only quote tool with no output schema, the description is nearly complete: it covers pricing, billing intervals, authentication requirements, and a real edge case. It does not describe the exact response structure, but it references billing_options[].payable and is sufficient for correct selection and 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%, and the schema already gives an example value for plan_code. The description adds that the plan is a 'star365 plan' but does not add new constraints, allowed values, or formatting guidance beyond what the schema provides. The baseline of 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?

States that the tool returns the price and contents of one specific star365 plan in USDT, with monthly and annual variants. This clearly distinguishes it from purchase_intent and purchase_status, which are payment-flow tools, and identifies the resource being queried.

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?

Provides clear usage context: the operation is read-only and requires no account, so the agent knows it can invoke it without authentication or side effects. It also gives a practical instruction to check billing_options[].payable because cheap plans must be annual. It does not explicitly mention when not to use it or point to siblings, but the context is strong.

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