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

Annotations indicate readOnlyHint=true, which the description aligns with. Beyond that, it adds valuable context: inclusion of national insurance, the phasing out of credits, and the specific output breakdown (tax before credits, each credit, final amount, take-home pay). It also discloses limitations (only salary, below AOW age).

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 four sentences long, front-loaded with the primary purpose. Each sentence adds distinct information: the core calculation, the reason this tool differs from generic calculators, the specific tax rules, and the expected outputs. It is somewhat detailed but justified for a tax calculator with nuanced logic.

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 single optional parameter, no output schema, and read-only annotation, the description provides sufficient context to understand the tool's scope, inputs, and outputs. It explains the tax year (2026), the tax system (Box 1), eligibility, and the returned values, which is complete enough for an agent to select and invoke it correctly.

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?

The schema already provides 100% coverage with a detailed description of annualIncome (gross employment income, used for arbeidskorting, for those below AOW age). The tool description reinforces the 'salary-only' aspect but does not add significant new parameter semantics beyond the schema, so the baseline of 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 this is a 2026 Dutch Box 1 salary tax calculator that includes the general tax credit and employment tax credit, and outputs tax before credits, each credit, final amount, and take-home pay. It distinguishes itself from generic calculators and sibling tools like netherlands_30_percent_ruling by focusing on salary tax for employees below AOW age.

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 explicitly defines the target user (employees below AOW age) and scope (salary-only), and implicitly contrasts with generic calculators that miss the credits. However, it does not name specific alternative tools or provide 'when not to use' beyond the salary/AOW constraints, so it is clear but not fully explicit.

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