housing_payoff_calculate

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

Annotations already declare readOnly/idempotent/non-destructive, so the baseline is covered; the description still adds real behavior: results are not stored, non-amortizing or over-max-period outcomes must not be interpreted as full repayment, and further schedule pages are fetched via schedulePage.nextOffset. That last point discloses a return field even though no output schema exists.

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 purpose, then the interpretation warning, then the paging hint. No filler, though the caveat sentence is terse enough that it needs the reader to infer the edge-case semantics.

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 no output schema, the description steps in to explain the two most dangerous result interpretations and how to page through the schedule, which is the critical information for this tool. It stops short of describing the shape of the result (months, totals), but an agent can still call it correctly.

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 reported at 0%, so the description must carry parameter meaning, and it largely does not. It hints that scheduleOffset/nextOffset drive paging, but leaves scheduleLimit, maxMonths, and the nested payoff object (principal/rate/payment) unexplained beyond what the raw schema shows.

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 gives a specific verb+resource pair: calculating the payoff period for principal+interest under a fixed monthly payment, and adds the scope fact that nothing is persisted. It is clearly distinct from the save/get siblings, but it does not differentiate itself from the other calculate siblings (housing_loan_calculate, housing_finance_calculate, housing_affordability_calculate).

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: it states the tool is non-persisting and warns not to read non-amortizing or max-period-exceeded results as full payoff, which is useful caveat context. However, it never says when to pick this over the sibling calculators, nor what inputs make it appropriate.

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