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

With no annotations, the description carries the full disclosure burden. It helpfully lists the main outputs and connects extra payments to interest savings, but it does not state assumptions such as ignoring fees/taxes, compounding frequency, or output formatting. This is adequate but not fully transparent.

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 a single, compact sentence that front-loads the resource and enumerates the key outputs. There is no filler or redundant wording, making the tool's value easy to scan quickly.

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 no output schema and no annotations, the description should more thoroughly explain what the agent receives. It lists output categories, but does not define their units or structure, and it does not clarify assumptions or how the optional extraMonthlyPayment changes all outputs. It is minimally viable but has clear gaps.

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 100%, so the schema already documents principal, interestRate, termYears, and extraMonthlyPayment. The description adds a small amount of meaning by linking extraMonthlyPayment to 'interest saved,' but it does not substantially enhance the parameter semantics beyond the schema.

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 identifies the resource ('any fixed-rate loan') and the computed outputs (monthly payment, total interest, payoff time, interest saved by extra payments). It is clear, but it does not include an explicit verb or directly contrast with specialized siblings like calculate_mortgage or calculate_car_loan, so differentiation is more implicit than explicit.

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?

'Any fixed-rate loan' provides an implied scope and suggests broad applicability, but the description does not say when to prefer this generic calculator over the many specialized loan siblings. No alternative conditions, exclusions, or 'use X instead' guidance is present.

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