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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds genuinely useful behavior not in annotations: the 13/3 weeks-per-month payroll convention and the exact set of returned figures (hourly wage, minimum wage, required monthly pay, shortfall). Missing only things like which minimum-wage table/version is used or edge-case handling.

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 dense sentences: scope constraint, purpose, outputs, calculation convention, and exclusion — all front-loaded with zero filler.

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?

Although there is no output schema, the description explicitly names the four returned values, so an agent knows what it will get. Combined with fully documented inputs and read-only annotations, nothing material is missing for correct invocation.

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 100% with per-parameter descriptions, patterns and ranges, so the baseline is 3. The description restates the two main inputs and adds the interpretation convention (13/3 weeks per month) but gives no extra semantics for stichtag beyond what the schema documents.

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 ('Check a monthly salary and weekly hours against the German statutory minimum wage') and even enumerates the computed outputs. The 'Germany only' scope and the apprentice exclusion separate it cleanly from generic payroll siblings like arbeitgeberkosten or minijob.

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?

Gives clear applicability constraints ('Germany only', 'Not for apprentices (they have a minimum training allowance)'), which is real when-not guidance. It does not, however, name which sibling to use instead for those excluded cases, so it falls short of a full routing statement.

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