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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered and this is a safe deterministic calculation. The description adds jurisdiction and statutory-rule context (5.6 weeks, 28-day cap, 12.07% rate), but much of that overlaps the schema parameter text and it says nothing about the response shape or units of the result.

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?

A single front-loaded sentence plus a documentation URL; the tool identity and scope come first and every clause carries domain information with no filler. Nothing is padded or redundant.

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 an 8-parameter, zero-required calculator with full schema coverage and safety annotations, the description supplies the legal/domain framing an agent needs to choose it. It stops short of describing the output fields, which matters slightly since there is no output schema, but the linked web page partially covers that gap.

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 already carries meaning (e.g., the basis enum and the 12.07% accrual note on 'worked'). The description's mention of pro-rata days/hours and irregular hours loosely maps to those fields but adds no syntax, defaults, or constraints beyond the schema. Baseline 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?

States a specific verb/resource ("UK holiday entitlement calculator") and enumerates the exact computation scope: statutory 5.6 weeks capped at 28 days, pro-rata for part-time days/hours, starters and leavers, and 12.07% irregular-hours accrual. This clearly separates it from adjacent UK tools like redundancy_pay_calculator and salary_calculator without the agent needing to open any schema.

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 enumerated scenarios (part-time days/hours, starters/leavers, irregular hours) implicitly signal when the tool applies, which is useful. However, it never states when NOT to use it or names an alternative sibling (e.g., redundancy_pay_calculator for termination pay), so selection guidance is only implied.

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