calculate_affordability

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

With no annotations, the description must carry behavioral load, and it discloses the calculation model, the binding-constraint logic, and the fixed 3/5/10/20% down-payment scenarios. It does not state that the tool is a side-effect-free pure computation, but the methodology disclosure is substantive.

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?

Well front-loaded: the core purpose and governing rules lead, with mechanical Args/Returns structure after. The down-payment scenario detail is slightly extraneous but every part is readable and the purpose is not buried.

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 need not be elaborated, and the description still summarizes them. Combined with the methodology disclosure and all four parameters explained, an agent has what it needs, though sibling differentiation and usage conditions remain thin.

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 0%, so the description carries the full burden, and it does compensate: it clarifies that income is gross and pre-tax, that debts are existing monthly obligations, and that the rate is a percentage and the term is in years. Units and intent are added beyond the bare schema titles, though no valid ranges or edge-case handling are given.

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 precise verb (calculate) and resource (maximum affordable mortgage) and names the governing methodology (standard 28% front-end / 43% back-end DTI). This clearly distinguishes it from siblings like calculate_monthly_payment or get_amortization_schedule, which do not perform affordability inversion.

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 implied by the DTI-based affordability framing, but the description never states when to prefer this over siblings such as calculate_monthly_payment or compare_loan_scenarios, nor any prerequisites or exclusions. Adequate but leaves the routing decision to inference.

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