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

Since no annotations are provided, the description carries the full burden and excels by disclosing critical transactional behavior: it explicitly states the cost (0.001 USDC per call) and the necessary payment proof via x402.

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 dense and front-loaded, but it is slightly wordy given the complexity (covering function, output, cost, and payment method) in a single statement.

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 that the tool is a transactional calculation with dependencies (payment proof), the description is highly complete. It covers the calculation scope, the cost, and the payment workflow, leaving no major functional unknowns for the agent.

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?

Though schema coverage is 75%, the description provides high semantic value by detailing the complex payment flow required for the `paymentProof` parameter. This is vital context that goes beyond the schema definition.

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 core function: converting between simple APR and compounded APY. It also mentions the delivery of equivalent daily and monthly rates, making it highly specific.

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?

While the function is clear, it does not explicitly state when to use this tool relative to similar financial sibling tools (e.g., `compound_interest`). Usage guidance relies solely on understanding the conversion relationship.

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