calculate_uk_vat

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

No annotations are present. The description discloses the return format: '{amount_net, amount_gross, vat_amount, vat_rate_pct}'. Since this is a calculation tool with no side effects, the behavior is adequately transparent. It implies a read-only, deterministic operation.

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 two sentences: the first defines purpose, the second lists outputs and a reference to related tools. Every word adds value; no redundancy or fluff.

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?

With a simple input schema (3 parameters, all described), an output schema implied by the description, and no complex nested structures, the description covers all necessary information for correct usage. The mention of a sibling tool for further exploration is a bonus.

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?

All three parameters have schema descriptions (100% coverage). The description adds context by explaining the conversion between net and gross and listing the output fields, which the schema does not provide. This enhances understanding of how parameters relate to the tool's purpose.

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's function: 'Calculate UK VAT — convert between net (ex-VAT) and gross (inc-VAT) amounts.' It specifies the verb (calculate/convert), resource (UK VAT), and scope (net/gross conversion). The mention of 'UK VAT' distinguishes it from other VAT tools in the sibling list.

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?

Description includes 'See list_bundles for related 'finance-uk' calculators.' This hints at a grouping but does not provide explicit guidance on when to use this tool vs. other VAT calculators (e.g., calculate_vat_generic, calculate_belgian_vat). No exclusions or alternative recommendations are given.

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