calculate_perpetuity

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

No annotations provided, so description carries full burden. It discloses that the tool is a pure mathematical calculation (PV = PMT/r, etc.), implying no side effects or destructive actions. Could mention assumptions like constant growth rate or precision, but the transparency is adequate for a simple financial function.

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?

Description is very short (two sentences plus formulas) and front-loaded with the purpose. Every sentence earns its place. Could be slightly improved by listing parameters more clearly, but overall efficient.

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?

Given the tool's complexity (simple math), it covers the core purpose and formulas. Output schema is present (context says true), so description does not need to detail returns. Missing edge cases (e.g., growth_rate >= annual_rate) but otherwise complete.

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 description adds meaning beyond parameter names and types. It maps payment to PMT, annual_rate to r, growth_rate to g, and shows formulas. This clarifies that growth_rate is optional (default 0) for simple perpetuity. Adds significant value by explaining mathematical relationships.

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 uses specific verbs ('calculate present value') and clearly identifies the resource ('perpetuity'). It distinguishes from siblings like annuity and future value by explicitly stating 'infinite periodic payments' and providing formulas for simple and growing perpetuities.

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?

The description does not explicitly state when to use this tool over alternatives. It implies usage for perpetuities but lacks guidance on comparing to annuity or other time-value-of-money tools. The context of sibling tools provides implicit contrast, but the description could benefit from highlighting scenarios (e.g., 'Use for perpetual cash flows, not for finite annuities').

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