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

With no annotations, the description carries the full behavioral burden. It does add real context by disclosing the paid/trial gating per signed wallet, but it omits important behavior such as whether the returned rate is a decimal or percentage, how non-convergent or multiple-root cashflows are handled, and what happens on invalid input.

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?

Front-loaded with purpose and example in two compact sentences with no filler. The emoji and pricing tail are minor decoration but do not obscure the core instruction.

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?

A three-parameter tool with no annotations and no output schema needs the description to resolve input format, parameter choice, and return shape. Instead the array-versus-string conflict and undefined behavior for edge cases remain unresolved, so an agent could easily call it incorrectly.

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% and three parameters exist (flows, cashFlows, cashflows) with no descriptions. The description says to provide an "array" with example "[-1000,300,300,300,300]", yet the schema types all three as strings, and it never says which of the three aliases to use or whether a JSON-encoded string is expected — leaving the caller to guess.

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 Internal Rate of Return (IRR) from a cashflow series." This clearly separates it from sibling finance tools such as x402-npv-calc, x402-roi-calc, and x402-cagr, though it does not name those alternatives explicitly.

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 guidance on when to choose IRR over NPV/ROI/CAGR, no prerequisites or constraints mentioned. The only conditional information is the "5 free trial calls per signed wallet" payment note, which is about access, not usage selection.

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