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

No annotations are provided, so the description carries the full disclosure burden. It does reveal the core behavior - the computation performed and that the result is a percentage - which is the most relevant behavior for a pure calculator, but it says nothing about error handling (e.g. division by zero when value is 0) or input format flexibility.

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 tight sentences, front-loaded with the tool name and formula before the input instruction. No filler; every clause conveys usable information.

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?

For a stateless two-input calculator with no output schema, the description supplies everything needed to invoke it: the formula, the output unit (percentage), and which values to supply. Only the zero/edge-case behavior for 'value' is left unaddressed.

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 nominally 100%, but the schema descriptions are generic placeholders ('Noi to process', 'Value to process'), so the description is the only source that decodes them into 'Net Operating Income' and 'property value' and clarifies which is the numerator. That is real added meaning 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?

States a specific verb and resource ('Calculate the capitalization rate') and goes further by giving the exact formula (NOI divided by property value, as a percentage). This distinguishes it from the hundreds of sibling calculators despite the generic x402- naming convention.

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?

'Provide noi and value' tells the agent what inputs are needed, which implicitly signals when the tool applies, but there is no explicit statement of when to use this versus related finance tools (e.g. x402-roi, x402-npv-calc) and no prerequisites or exclusions.

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