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

Annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world), so the description need not restate safety. It adds domain context (Belgian statutory benefit) but no behavioral specifics like the legal caps applying to contributions or whether defaults reflect current law.

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?

Purpose is front-loaded in a single crisp sentence. The trailing return-field enumeration is largely redundant given an output schema exists, and the trailing '...' makes it incomplete rather than exhaustive, but the overall length is reasonable.

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 low-complexity calculator with 0 required params, 100% schema coverage, an output schema, and complete annotations, the description covers what the agent needs to select and call it. The main missing piece is disambiguation from other Belgian finance calculators.

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% — all three parameters (days_per_month, employee_contribution, employer_contribution) carry descriptions, defaults, and min/max bounds in the schema. The description adds nothing about their semantics, so the 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 (Calculate) and resource (Belgian meal voucher / cheque-repas benefit), naming both the French and Dutch terms. Against a huge sibling set of generic 'calculate_*' tools, this is clearly distinguished as a country-specific payroll benefit 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?

It points the agent to list_bundles for related 'finance-belgique' calculators, which is a mild routing hint. But it never states when to choose this tool over, say, calculate_belgian_salary or calculate_employer_cost_fr, nor any exclusions or prerequisites.

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