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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds that charges and vacancy are applied to produce a net figure, plus the returned fields, but gives no behavioral detail beyond what the annotations and output schema convey.

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 short sentences, no waste, with the calculation purpose front-loaded before the return-value note. The trailing list_bundles pointer is slightly tangential but plausibly earns its place as a discovery aid.

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 deterministic pure-calculation tool with an output schema, fully specified required parameters with bounds, and read-only annotations, this is largely sufficient. The only real gap is the absence of explicit disambiguation from the gross-yield siblings in a family of closely named rental tools.

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 all four parameters (monthly_rent EUR, purchase_price EUR, annual_charges, vacancy_rate percent) are already documented with units and bounds. The phrase 'after charges and vacancy' loosely maps to two parameters but adds no new meaning such as calculation order or whether vacancy is applied on rent or on net income.

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 and resource ('Calculate net rental yield') and adds the defining modifier 'after charges and vacancy', which distinguishes it from gross-yield variants. However, it never names the closest sibling (calculate_rental_yield_gross or calculate_rental_yield), so the distinction must be inferred from the word 'net'.

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?

No explicit when-to-use or when-not-to-use guidance. The only routing hint is 'See list_bundles for related immobilier calculators', which points at bundle discovery rather than telling the agent when this tool beats calculate_rental_yield_gross, calculate_rental_yield, or calculate_rental_profitability.

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