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

With no annotations, the description carries the full burden. It discloses the key output values and the optional verify=true certification feature. However, it does not mention assumptions (e.g., property tax, insurance) or the exact structure of the DTI scenarios table, leaving some behavioral aspects implicit.

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?

The description is two sentences, front-loaded with the core purpose and method, and includes a brief note about certification. Every sentence provides value with no wasted words.

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 calculator with 8 required parameters, no output schema, and no annotations, the description is too sparse. It does not explain all inputs or fully define the return value's structure (only mentions max loan, price, and a table). More detail is needed for an agent to correctly invoke and interpret results.

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?

The schema has 8 parameters with 0% description coverage. The description only explicitly mentions 'income, rate, and debts', omitting critical parameters like frontEndDtiPct, backEndDtiPct, termYears, and downPayment. The 28/36 DTI rule hints at the ratio meaning, but does not compensate for the lack of parameter documentation.

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 clearly states a specific verb and resource: 'Find out how much house you can afford' using the '28/36 DTI rule'. It names outputs (max loan, price, DTI scenarios table) and is easily distinguished from sibling calculators like car_affordability_calculator or rent_affordability_calculator.

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 gives a clear context for when to use this tool: to determine home affordability based on income, rate, and debts. It does not explicitly mention alternatives or when not to use it, but the use case is unambiguous.

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