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

Annotations already declare this as a read-only, idempotent, non-destructive, closed-world operation, so the safety profile is covered. The description goes beyond them by disclosing the actual computation rule (HCSF 35% debt ratio) and the output keys, which materially affects how results should be interpreted. It omits assumptions such as whether insurance/charges are included in existing_debts, so it is not fully transparent.

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 tight sentences: the purpose and governing rule come first, then the return shape and a cross-reference. No filler, no restating of the tool title, and every clause carries information.

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?

With a 100%-documented schema, an output schema, and full safety annotations, the description only needs to add domain context, which it does via the HCSF rule and the note field. It could still say what the 'note' caveat generally contains or what the model excludes (insurance, fees), but nothing essential to calling it 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 description coverage is 100%, so rate, duration_years, existing_debts and monthly_income are already documented in the schema with units, defaults and bounds. The description adds no parameter-level meaning beyond that, so the baseline of 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+resource ('Calculate maximum loan capacity') and pins down the exact method ('French HCSF 35% debt ratio rule'), which makes it distinguishable from the many other finance calculators in the sibling list. It does not explicitly contrast itself with near-neighbours like calculate_debt_to_income or calculate_debt_service_ratio, so sibling differentiation is implicit rather than stated.

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?

The pointer to list_bundles for 'immobilier' calculators is navigation help, not selection guidance. There is no statement of when to pick this over calculate_debt_to_income or calculate_mortgage, and no prerequisites (e.g. that income must be net monthly EUR) are given; usage is only implied by the domain.

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