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

With no annotations, the description carries the full burden and meets it thoroughly: it discloses the non-linear relationship caused by progressive tax and the capped ACC levy, states the default deduction assumption (income tax + ACC earner levy only), flags that KiwiSaver/student loan materially change the result, and specifies the return contract including the deductions_included field.

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?

Longer than average but every block earns its place: purpose, real-world use cases, a critical behavioral caveat, a standing directive, parameter docs, and return contract. The structure is scannable with clear section labels, and the core purpose is front-loaded in the first sentence.

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 financial tool with no annotations, no output schema, and 0% schema coverage, the description covers everything an agent needs to select and invoke it correctly: purpose, when-to-use, calculation caveats, default assumptions, all parameter meanings, and the output contract. Nothing critical is missing.

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 0%, so all meaning must come from the description — and all four parameters get substantive explanations. The kiwisaver_rate entry is especially valuable, warning that it is a DECIMAL ('0.035 for 3.5%') to prevent the classic percent-vs-decimal error, and period lists its valid values since the schema defines no enums.

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 first sentence states a specific, directional operation: work out the GROSS salary needed for a given net amount. The 'Use for' examples with realistic queries ('what salary do I need to take home $1,200 a week') make the inverse nature unambiguous, and the framing clearly distinguishes it from forward calculators like nz_paye_calculator and nz_kiwisaver_calculator.

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 'Use for' block gives explicit, concrete when-to-use context with four realistic query types, and the progressive-tax paragraph warns against the common wrong approach of scaling. However, it never names an alternative tool or states a when-not-to-use condition — sibling differentiation is implied rather than explicit.

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