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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely new behavioral context: the result is indicative only, thresholds are dated, checkpoints are returned step-by-step, and the outcome is not an entitlement. It stays consistent with openWorldHint since official thresholds are external. It stops short of describing precision or jurisdiction limits, so a 4 rather than 5.

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 tightly packed sentences with no filler: the first states what is computed and from what, the second carries the legal qualification. The purpose is front-loaded and the caveat is placed where it will still be read.

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?

An output schema exists, so return values need not be explained, and annotations cover safety; the description therefore only needed to supply the computational input list and the caveat about non-entitlement, which it does. Minor gaps remain around jurisdiction/residency eligibility and currency, but nothing essential to calling it correctly is missing.

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 only 50% — householdSize and dependentChildren have no schema descriptions — but the description explicitly names both, plus 'previous-year monthly net income', so the undocumented parameters are disambiguated. It does not specify units or accepted ranges, which the schema covers for the other two fields, so it does not exceed a 4.

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?

The description gives a specific verb and resource — calculating the Luxembourg rent subsidy (subvention de loyer) — and enumerates the four determinants, so an agent knows exactly what computation is being performed. It does not explicitly name how it differs from near-neighbours such as calculate_rent_ceiling or get_affordability, which keeps it below a 5.

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?

Relevant usage is only implied: the listed inputs (household size, income, rent) signal the scenario, but there is no explicit when-to-use, when-not-to-use, or pointer to an alternative sibling. The closing 'Ministry decides' sentence is a legal caveat rather than routing guidance.

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