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

With no annotations, the description carries the full behavioral burden. It reveals the computation model but omits whether the call is a pure read, what currency/units convention applies, what output shape or precision to expect, and what the 'signed wallet' trial constraint actually requires. The trial/payment note is the only extra context, and it is vague.

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 core definition is one front-loaded sentence with no filler. The appended emoji/trial clause is promotional rather than descriptive, which costs it a point but doesn't bury the useful text.

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 output schema, no annotations, and four fully undocumented string parameters for a quantitative finance calculation. An agent could guess a reasonable call, but the definition leaves units, result format, and input semantics unspecified for a tool whose correct results depend on exactly those conventions.

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% and all four parameters (face, rate, years, coupon) are bare strings, yet the description never explains them — e.g. whether 'rate' is the coupon rate or the yield, whether 'years' is maturity, or expected units (decimal vs percent). Nothing is added over the schema, leaving a genuine ambiguity unresolved.

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 ('Computes bond duration') and even names the measure ('present-value-weighted average time of cash flows'), which pins it down as Macaulay-style duration. It does not, however, distinguish itself from near siblings such as x402-bond-convexity, x402-bond-price, x402-bond-yield, or x402-duration, so an agent must infer the split.

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 and no reference to alternatives, even though the sibling list contains closely related bond and duration tools. The only usage-flavored text is a payment promo ('5 free trial calls per signed wallet'), which says nothing about when this tool is the right choice.

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