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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds the output shape ({income_ceiling, ptz_max_pct_of_operation, note}), but an output schema already exists, making this largely redundant. No additional context about limits or edge cases is provided, so the bar for added value is barely cleared.

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, with the core purpose front-loaded ahead of the cross-reference. The 'Returns: {…}' block partially duplicates the output schema, which is the one segment that does not fully earn its place.

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 read-only deterministic calculator with complete annotations, a full output schema and 100% parameter description coverage, the description supplies everything an agent needs to decide and invoke. It is complete, though it could have noted the French-only applicability constraint more explicitly.

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% – household_income, household_size (including the 1-5 clamp), and the zone enum are all documented in the schema itself. The description adds no parameter-level meaning beyond the schema, 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 and domain resource ('Check French PTZ (zero-rate loan) eligibility and maximum amount'), which is immediately distinguishable from generic siblings like calculate_loan_payment or calculate_loan_to_value. An agent can identify the niche (French zero-rate property loan) without opening the schema.

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 description says what it computes and points to list_bundles for related 'immobilier' calculators, which gives implied navigation context. However, it never states when this tool applies versus the many other French property/finance calculators in the sibling list (e.g. calculate_pinel_tax_reduction, calculate_housing_aid), so usage is only implied rather than explicit.

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