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

With no annotations provided, the description carries the full burden of behavioral disclosure. It only labels the tool as a 'calculator,' implying a non-destructive computation, but says nothing about output format, units, how the redundant parameters behave, or whether there are side effects. This is a thin signal for a 7-parameter tool.

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 six-word description is under-specified rather than genuinely concise; it front-loads the 'Loan' label but carries minimal substance for a tool with 7 parameters and no annotations. This is closer to a stub than an appropriately sized definition.

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 7-parameter tool with zero required parameters, no annotations, no output schema, and ambiguous parameter duplication, the description is entirely inadequate. An agent cannot determine valid input combinations, expected output, or how this differs from x402-loan-payment, x402-loan-amortize, or x402-mortgage-calc, all of which appear in the sibling list.

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 every parameter description is a placeholder ('Apr to process', 'Rate to process'), and the description adds no meaning. With zero required parameters and three overlapping groups (apr/rate/annualRate, term/years, amount/principal), the description fails to disambiguate which inputs are needed or how they map to the calculation.

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 states the tool is a loan calculator producing monthly payment and amortization, which names the resource and output. However, it does not distinguish this from the near-identical siblings x402-loan-payment, x402-loan-amortize, and x402-mortgage-calc, so an agent cannot tell which tool handles which subset of loan math.

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?

There is no guidance on when to use this tool versus the many overlapping loan/finance siblings, no mention of which parameters constitute a valid input, and no exclusions or prerequisites. The agent is left to guess whether to call this or x402-loan-payment, x402-loan-amortize, or x402-mortgage-calc.

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