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

No annotations are provided, so the description carries the full burden. It does disclose the return shape (year-by-year net worth, break-even year), but stays silent on modeling assumptions that materially change results — maintenance, property tax, transaction costs, whether rent grows annually or compounding of investReturn — leaving the agent unable to predict output behavior fully.

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, front-loaded with the core purpose, followed by a worked example. The example JSON is bulky but earns its place given nine required numeric parameters. No filler or marketing language.

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 and no annotations, the description does the necessary work by naming the return values (year-by-year net worth and break-even year). It falls short of fully complete for a financial model by omitting the cost assumptions embedded in the calculation, which an agent may need to set user expectations.

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 the baseline is 3. The description adds value by grouping the nine inputs semantically (rent, price, down payment, loan terms, growth assumptions) and by providing a concrete example input with realistic values that shows unit scale and typical magnitudes beyond the schema's unit notes.

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 computation (year-by-year net worth of buying vs renting) plus the key output (break-even year), and enumerates the input domain. This is clearly distinguishable from siblings like emi, downPayment, or sensitivity.

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 example input implies a full buy-vs-rent scenario comparison, but there is no explicit when-to-use guidance, no statement of when a sibling like sensitivity or emi would be the better choice, and no prerequisites. Usage must be inferred from the description and example.

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