rent_vs_buy

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

No annotations are provided, so the description carries the burden. It explains the calculation methodology (standard annuity, principal+interest only) and lists exclusions (insurance/fees/taxes/maintenance/appreciation). It also states default values, which is useful for users. This is more transparent than many tools.

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 concise, with 3 sentences that are information-dense. It front-loads the purpose, then provides methodological context, defaults, and output. Every sentence serves a purpose with no fluff.

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?

Given that there is no output schema and annotations are missing, the description does an excellent job of covering what the tool does, how it works, what it excludes, default parameters, and what it returns. This is sufficient for most users to decide whether to use it.

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%, and descriptions already include defaults and units. The description adds context about the defaults matching the site, and explains how each parameter fits into the calculation. It doesn't repeat schema details, but the schema already provides adequate semantics, so a score of 4 is appropriate.

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 the tool's purpose: comparing monthly cost of buying vs renting. It specifies the exact inputs (price, rent), the computation (mortgage payment), and the output (monthly buy payment, rent, difference). It distinguishes itself from siblings like rent_affordability by focusing on cost comparison rather than affordability.

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 provides usage context by noting that it uses the same engine as the /finance page, which implies it's for general cost comparison. However, it doesn't explicitly mention when not to use it (e.g., when taxes or maintenance should be included). It does indicate that it excludes certain factors, which helps users understand its limitations.

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