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

With no annotations, the description carries the full burden, and it delivers two useful behavioral facts: the calculation methodology and the fact that the result contains a calculator_url that must be surfaced as a clickable markdown link. It does not disclose what else the result contains or the assumptions behind the price (taxes, insurance, HOA), which is a meaningful gap for an affordability calculation.

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?

Two sentences, zero waste. Purpose is front-loaded and the operative instruction about the calculator_url follows immediately, with the IMPORTANT flag making the mandated behavior unmissable.

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 7-parameter calculator with full schema coverage and no output schema, the description covers purpose, method, and the key output element to surface. The remaining gap is the absence of stated assumptions (whether property tax, insurance, or HOA are included in the affordable price), which materially affects interpretation of the result.

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 100%, so baseline is 3, but the description earns credit by naming the 28/36 rule, which explains the meaning of the front_ratio_pct and back_ratio_pct parameters and their defaults. It also grounds inputs in household income, framing the required annual_income field correctly.

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?

States a specific verb and resource: the maximum home price affordable from household income, qualified by the 28/36 rule. This is clearly distinct from calculate_mortgage (payment sizing) and calculate_car_affordability, though the description does not explicitly name a sibling or state the contrast.

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 through the opening purpose statement; there is no explicit when-to-use versus alternatives guidance (e.g., versus calculate_rent_vs_buy or calculate_mortgage). The bolded IMPORTANT instruction is about presenting results, not about selecting this tool over another.

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