Calculate IVA (El Salvador, 13%)

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

The description discloses the rounding to 2 decimals and the return object {subtotal, iva, total}. Since no annotations are provided, the description carries the full burden, and it adequately covers the behavioral traits for a simple calculation, though edge cases or errors are not mentioned.

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?

Three concise sentences, front-loaded with the purpose. Every sentence adds essential information without redundancy or excess words.

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 simplicity, the description covers all needed aspects: purpose, parameter behavior, return structure. No output schema exists, but the description explains the return object. Sibling tools are unrelated, so no additional context is 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 coverage is 100%, providing baseline 3. The description adds value by explaining the default behavior of includesIva (defaults to false) and how amount is interpreted in each mode, beyond the schema's type and required information.

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 explicitly states it computes El Salvador IVA at 13%, clearly distinguishing the tool from sibling tools like list_dte_types, validate_dui, and validate_nit. It specifies the two modes (net vs. gross amount) and the return structure.

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 explains when to use the tool (when needing IVA calculation for El Salvador) and the two scenarios based on includesIva. It does not explicitly mention when not to use, but the sibling tools are unrelated, making the context clear.

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