calc_vat

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

No annotations provided, so description fully covers behavior: states read-only, offline, single-rate line, no side effects. Describes return object fields and includes an example. Exceeds required disclosure.

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?

Well-structured with clear sections (purpose, when to use, when not, parameters, returns, limitations, example). Every sentence is informative and necessary. Front-loaded with core action.

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 3 parameters and an output schema, the description is fully complete: covers all use cases, exclusions, parameter semantics, return format, limitations, and provides an example. No 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?

Schema describes all 3 parameters with 100% coverage. Description adds context for each parameter (e.g., 'base sum in RUB (net for add, gross for extract)') and demonstrates usage with example. Adds value beyond schema.

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?

Clearly states the tool computes Russian VAT (НДС) with two modes (add to net or extract from gross). Distinguishes from sibling tools like calc_insurance_ip by focusing specifically on VAT.

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 explicit 'When to use' (invoice line, USN taxpayers, sanity check) and 'When NOT to use' (VAT declaration, multi-rate, export/zero-rate, mixed lines). This is comprehensive guidance for correct selection.

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