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

With no annotations, the description carries the full behavioral burden. It discloses the 'approximate' nature of the computation and the free-trial/per-signed-wallet payment model, which is useful, but says nothing about the yield convention used, units of the result, error behavior, or whether any parameter is actually required.

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 efficient sentence that front-loads the purpose and then lists inputs. The trailing emoji/trial-call blurb is marketing noise that does not earn its place in the functional description.

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 computation tool with 0% schema description coverage and no output schema or annotations, the description is thin: it never states the output's form (decimal vs percentage), nor what happens with missing or invalid inputs. Only the face default is fully resolved.

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 0%, so the description must compensate. It names all four parameters (coupon, face, price, years) and supplies a meaningful default for face (100), which is real added value. However, it gives no units, formats, or typical ranges, so half the semantic burden is still unmet.

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 ('Computes') and resource ('approximate bond yield') and enumerates the four inputs, so the agent knows exactly what the tool produces. It does not differentiate itself from close siblings like x402-yield-to-maturity, x402-current-yield, or x402-bond-price, which an agent would want to distinguish.

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?

No when-to-use guidance and no naming of alternatives, despite a crowded sibling space of yield/duration/convexity tools. The only context offered is a payment promo line, which does not help selection.

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