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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds nothing beyond that — it doesn't say the result is an estimate, what assumptions are made (e.g., fixed-rate amortization), or how the optional rentalIncome parameter affects the output.

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?

A single short sentence with zero waste, but it is under-specified rather than well-structured — there is no front-loaded scope statement or qualifier to make the brevity productive.

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 five parameters, no output schema, and no explanation of return values, the description leaves a real gap: an agent cannot tell whether the result is a monthly payment, total interest, or a price estimate. For a calculator tool whose whole value is its output, this is a meaningful omission.

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 description coverage is 80%, so the schema itself documents price, rate, years, and rentalIncome. The description adds no meaning beyond those fields, and notably does not clarify that downPayment is the one undescribed parameter or that rentalIncome is optional.

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 verb ("Calculate") and a resource ("mortgage price"), so the general intent is inferable. However, "mortgage price" is imprecise — the tool almost certainly returns an estimated payment, not a property price — and nothing distinguishes it from the sibling 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?

No guidance on when to use this versus affordability_calculator, which is the obvious overlapping sibling in the tool list. No prerequisites, no mention of what input scenarios it fits (e.g., monthly payment estimation for a specific listing).

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