Calculate VAT (Value Added Tax).
| Name | Required | Description | Default |
|---|---|---|---|
| amount | Yes | Amount | |
| vat_rate | No | VAT rate percentage | |
| inclusive | No | Is amount VAT inclusive? |
| Name | Required | Description | Default |
|---|---|---|---|
| vat_rate | Yes | ||
| net_amount | Yes | ||
| vat_amount | Yes | ||
| gross_amount | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so description must convey behavior. It only says 'Calculate VAT' without explaining rounding, handling of inclusive/exclusive amounts, or return value structure.
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?
Extremely short (one sentence) but omits important details like calculation formula or return types. Could be more informative without sacrificing conciseness.
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 parameter count (3) and presence of an output schema, the description should explain what the tool returns (e.g., calculated VAT amount, formatted string). Currently missing this context.
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?
Input schema covers all 3 parameters with descriptions; schema description coverage is 100%. The description adds no additional semantics beyond what the schema provides, so 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 tool calculates VAT, a specific financial calculation. It distinguishes from sibling tools which include other calculations like calculate_tip, calculate_margin, etc.
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?
No guidance provided on when to use this tool vs alternatives. The description does not specify prerequisites, typical use cases, or when not to use it.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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