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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is fully covered structurally. The description adds little beyond that: the return-field list duplicates the existing output schema, and the amortization mention simply restates the with_schedule parameter. No additional behavioral context (rounding, currency assumptions, edge cases) is given.

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 the core computation, followed by the return shape and a pointer. Nothing is padded, though the return-field enumeration is largely redundant given the output schema.

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 annotations covering safety, a full output schema, and 100% parameter documentation, the definition gives the agent everything needed to invoke the tool correctly. The only missing element is disambiguation from sibling loan calculators, which is minor given the complete structured metadata.

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% and each parameter carries its own description with min/max bounds, so the schema does the heavy lifting. The description only alludes to the optional amortization schedule, which the schema's with_schedule field already documents more precisely (first 12 months + last month). 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?

The description states a specific verb and resource ('Calculate mortgage/loan monthly payment, total cost') and enumerates the computed outputs, so the purpose is unambiguous. It does not, however, distinguish itself from close siblings like calculate_us_mortgage or calculate_loan_payment, leaving the agent to infer which one applies.

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?

There is no statement of when to use this tool versus the many adjacent loan calculators (calculate_loan_payment, calculate_us_mortgage, calculate_mortgage_insurance). The only routing hint is a pointer to list_bundles for 'finance-france' calculators, which is discovery rather than usage guidance.

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