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 fully covered without description help. The description adds that multiple derived metrics are returned in one call, but says nothing about currency, rounding, payment timing, or the annuity assumption behind 'monthly repayment'.

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?

A single dense sentence with no filler, and the outputs are front-loaded ahead of the input list. It reads as a noun-phrase fragment rather than a sentence, but 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?

There is no output schema, so the description's enumeration of return values is genuinely necessary and it delivers them. For a four-required-param pure calculation with full schema coverage and complete annotations, the only real gap is the unaddressed overlap with loan_repayment_calculator.

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 of the four parameters carries its own description plus min/max bounds, so the schema does the heavy lifting. The description only restates the field list (price, deposit, rate, term) without adding format, unit or convention guidance beyond the schema.

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 names the specific computed outputs (monthly repayment, loan-to-value, total interest, interest-only payment) and the exact inputs, so an agent knows precisely what it produces. It does not, however, distinguish itself from the near-identical sibling loan_repayment_calculator, leaving the agent to guess which to pick.

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?

Usage is only implied: an agent can infer this is the tool for mortgage scenarios from the enumerated outputs. There is no explicit when-to-use statement and no mention of the obvious alternative, loan_repayment_calculator, which is a real ambiguity given the sibling list.

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