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

No annotations are provided, so the description carries the full burden. It adds useful context by disclosing the fee components (3% service fee + payment fee) and the comparison aspect, and notes it's a browser-based tool. However, it does not describe the interaction details (e.g., form inputs, output format, or lack of persistence), which would improve transparency.

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 a single, compact sentence that is front-loaded with the primary purpose, followed by the plan comparison and a parenthetical note about being browser-based. Every word contributes value, with no redundancy or filler.

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?

Given the tool's low complexity (0 params, no output schema, no annotations), the description adequately covers the core purpose, fee details, and plan comparison. It could be slightly more complete by mentioning the exact payment fee rate or user interaction flow, but these are minor gaps.

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?

With zero parameters, the schema coverage is trivially 100%, and the baseline for 0 params is 4. The description adds meaning by explaining what the calculator does, indirectly indicating what user inputs might be needed (e.g., sales amount, plan type), even though it doesn't enumerate them.

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 it calculates profit after service fees (3%) and payment fees, and compares Standard/Growth plans. This is a specific verb+resource (BASE fee calculator) that distinguishes it from other fee calculators like rakuten-fee-calculator or mercari-calculator.

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 implies the tool is for BASE fee and profit calculations, and the plan comparison suggests when it's relevant, but it doesn't explicitly state when to use this tool vs alternatives or provide exclusions. No sibling mentions or alternative references are given.

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