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

With no annotations, the description carries the full behavioral burden. It usefully names what is returned (payment, total interest, amortization schedule) and mentions the signed-wallet trial pricing, but says nothing about error behavior, rate limits, or what happens when the loan cannot be computed. For a mutation-free computation tool this is thin.

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?

A single front-loaded sentence covering action, inputs, and outputs, followed by a short pricing tag. No filler, though the emoji trial note is marketing noise rather than tool guidance.

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?

No annotations, no output schema, and six fully undocumented string parameters with duplicated semantics. The description does not fill the gap left by the empty schema, so an agent cannot confidently decide which parameter names to send.

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 description coverage is 0% across 6 parameters, so the description must compensate and does not. It names three concepts (principal, annual rate percent, years) but the schema exposes six params forming apparent aliases (principal/amount, rate/apr, term/years) with all-string types and zero required fields; the description never explains these duplicates or which form to use.

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 output set: 'Computes equal monthly loan payment, total interest, and an amortization schedule from principal, annual rate percent, and years.' The resource and results are unambiguous. It does not, however, distinguish itself from close siblings like x402-loan-payment, x402-loan, or x402-mortgage-payment, which compute overlapping payment figures.

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 when-to-use guidance, no prerequisites, and no routing to alternatives among the many loan/mortgage siblings. The only usage-adjacent statement is the pricing note about 5 free trial calls, which is not a selection criterion.

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