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

Annotations already establish readOnly, idempotent, non-destructive behavior, so the safety bar is met. The description adds value beyond that by disclosing the comparison basis (payment, total cost including interest plus fees, estimated APR) and the equal-cash sizing methodology, though it says nothing about precision, rounding, or error cases.

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, no filler: the first defines the operation and its fair-comparison mechanic, the second supplies the motivating question. The most important scoping detail is front-loaded.

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, the description usefully enumerates what is returned (payment, total cost of borrowing, estimated APR) and explains the equal-cash premise. It is nearly complete, though it omits how fee_deducted and fee_pct interact with the sizing rule, which is the terminology an agent must reason about.

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 50% (annual_rate_pct and months are undocumented). The description compensates by explaining the critical normalization semantics – that offers are re-sized so cash received is equal – which is exactly the property that makes the comparison valid and is not captured anywhere in 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?

States a specific verb (compare) plus the resource (loan offers), the scope (two to four offers), and the normalization rule (each offer sized so the borrower receives the same cash), then names the three comparison outputs. An agent can distinguish this from siblings like loan_payment or average_loan_rates immediately.

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 gives an explicit triggering scenario: deciding whether a lower rate with an origination fee beats a higher rate without one. It says when to use it clearly, but never names an alternative tool to use instead or states when-not to use this one.

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