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 disclosure beyond that: the exact estimation assumptions (ONSS 13.07%, annual personal income tax, single filer, no municipal surcharge) and the internal endpoint it mirrors, which tells the agent the result is an estimate rather than a payroll-grade figure.

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?

Front-loaded with the conversion statement, followed by assumptions, a brief return enumeration, and a related-tools pointer. Dense but every clause carries information; the return-field list is somewhat redundant given an output schema exists, which keeps it from a 5.

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 single-parameter, read-only calculator with an output schema, the critical missing piece would be the estimation assumptions — and those are supplied explicitly (single filer, no municipal surcharge). Remaining gaps are minor, e.g. no note on precision or whether other filing statuses are supported.

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% with a single required parameter (gross_monthly, in euros) fully documented, so the baseline of 3 applies. The description confirms the euro currency and monthly basis but adds no syntax or edge-case guidance beyond the schema.

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+scope: convert Belgian gross monthly salary to net salary. It is clearly distinguishable from siblings such as calculate_belgian_income_tax and calculate_belgian_social_contributions, which compute only a component rather than the full gross-to-net conversion.

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?

Usage is implied (Belgian gross-to-net estimation) and the description cross-references the 'finance-belgique' bundle via list_bundles, but it never states when to prefer this tool over component calculators like calculate_belgian_income_tax or how it differs from calculate_french_salary / calculate_swiss_salary. No explicit exclusions or selection criteria are given.

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