Calculate Etsy seller fees by entering item price, shipping fee, and country. Returns total costs including transaction, payment processing, listing, and EU regulatory fees to assess net profit.
Calculate Etsy fees: transaction (6.5%) + payment processing (3.25%+$0.25) + listing ($0.20). EU adds 2% regulatory fee.
| Name | Required | Description | Default |
|---|---|---|---|
| country | No | ||
| itemPrice | Yes | ||
| shippingFee | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must disclose behavioral traits. It reveals the fee formula, which is useful, and implies a pure calculation with no side effects. However, it doesn't explicitly state that it is read-only, nor does it mention any limitations (e.g., currency, rounding, or whether shipping fees are included in the calculation). The disclosure is adequate but not exhaustive.
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, information-dense sentence followed by a brief EU addition. It front-loads the purpose and fee breakdown, and every clause adds value. No fluff or repetition.
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 simple calculator with no output schema and no annotations, the description covers the core formula and the EU variant, but leaves gaps: it doesn't specify what the output represents (likely total fees), the currency, or how shippingFee is treated. An agent might call it correctly, but some assumptions are required.
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 compensate. It mentions itemPrice implicitly via the fee breakdown and country via the EU note, but it never explains the role of shippingFee or explicitly maps each parameter to its meaning. The agent is left to infer that itemPrice is the sale price and that shippingFee may or may not affect fees, which is a significant gap.
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 a specific action (calculate Etsy fees) with the exact fee components (transaction, payment processing, listing, EU regulatory). It distinguishes from sibling fee calculators by naming the platform and the fee structure, making it unambiguous.
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 context is explicit: this tool is for Etsy fees. While it doesn't explicitly say 'use this instead of other calculators' or exclude other platforms, the description's specificity to Etsy provides clear context for when it applies. No exclusions are stated, but they aren't strictly needed given the name and description.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.