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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds the output shape (LTV %, risk level, PMI y/n), but that overlaps with the existing output schema and offers no behavioral context such as assumptions or input constraints beyond the schema's exclusiveMinimum.

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?

Three short sentences, front-loaded with purpose then usage then input/output summary; no filler, though the input/output recap is somewhat redundant given the schemas.

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 needn't be explained, and the description covers purpose, context, and the existence of related calculators. Sufficient for a two-parameter pure calculation, with only sibling routing left implicit.

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 100% with only two required numeric params; the description merely restates 'loan amount, property value' without adding units, ranges, or edge-case guidance beyond what the schema already documents.

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 ('Compute Loan-to-Value (LTV) ratio for mortgage risk'), which unambiguously distinguishes it from numeric siblings like calculate_cac_ltv_ratio and calculate_debt_to_income.

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?

Gives clear context ('use for mortgage application or PMI thresholds') and points to list_bundles for related 'immobilier' calculators, but does not explicitly contrast with adjacent tools such as calculate_mortgage or calculate_debt_service_ratio.

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