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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds that output is line-by-line with the applied rule and its source, plus employer cost, annualisation and stated assumptions – useful behavioral context, but it overlaps heavily with the existing output schema and says nothing about failure modes or input validation.

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?

Two sentences, front-loaded with the core operation, no filler. The second sentence is a long list of returned artefacts but each item is informative rather than decorative.

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 stateless, deterministic calculator with full schema coverage, rich annotations and an output schema, the definition is close to sufficient. Coverage gaps are minor: no mention that results are periodised/annualised inputs are mutually dependent, and no guidance on the DE/UK profile requirement linkage to country.

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 description coverage is 100%, so every parameter (country, gross, period, year, de/uk profiles) is already documented in the schema. The description only echoes 'gross pay', 'one pay period' and the country-specific algorithm, adding no syntax or constraint detail beyond structured data. Baseline 3 applies.

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?

States a specific verb and resource with direction and scope: 'Computes net pay from gross pay for one pay period with the country's official payroll algorithm.' That cleanly separates it from the inverse sibling calculate_gross_salary in substance, though the description never names an alternative explicitly.

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 gross-to-net direction and 'one pay period' scope imply the intended situation, but there is no explicit when-to-use, when-not-to-use, or routing to calculate_gross_salary / compare_net_salaries. Usage is inferable rather than stated.

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