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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering safety and idempotency. The description adds behavioral context by explaining the compounding-frequency dependency and the toNominal flag, making the transformation logic transparent. No contradictions or hidden side effects.

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, front-loaded sentence with no redundant words. It efficiently conveys both conversion directions and key parameter roles, earning its place without waste.

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 an output schema present and two required parameters, the description covers the primary use cases and the reverse operation. No missing information that an agent would need to select and invoke this tool correctly.

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 parameters are well-documented. The description adds meaning by explaining that ratePct is interpreted as nominal or effective depending on toNominal, and that periodsPerYear is the compounding frequency. This exceeds the baseline for high schema coverage.

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 converts a nominal annual rate to the effective annual rate (APY) for a compounding frequency, and also supports the reverse with toNominal. It uses a specific verb ('Convert') and resource, distinguishing it from sibling tools like compound-interest or after-tax-yield.

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 clear context for when to use the tool (nominal-to-effective or effective-to-nominal conversion) but does not explicitly exclude alternatives or name sibling tools. The dual-mode explanation gives strong guidance without being as explicit as a full when/when-not statement.

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