net_present_value

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

With no annotations provided, the description carries the full burden of disclosing behavior. It explains that period 0 is the initial investment, the rate is a decimal, and the currency is used for formatting. This adds valuable detail about input interpretation and output formatting, though it stops short of describing error handling or edge cases.

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 description is well-organized: a concise summary, the formula, and a clear args list. Every sentence adds necessary detail without redundancy. The structure is easy to scan and front-loads the core purpose.

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 moderate complexity and the presence of an output schema (so return values need not be described), the description is complete. It specifies the formula, period indexing, minimum cashflow length, and parameter formats, leaving no critical behavioral gaps.

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?

The input schema provides no descriptions (coverage 0%), so the description's parameter explanations are essential. It fully clarifies rate (decimal per period), cashflows (list of >=2 numbers with an example), and currency (ISO code for formatting), adding meaning far beyond the schema's bare type definitions.

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 clearly identifies the tool as computing Net Present Value (discounted cash flow) of a periodic cashflow series. It provides the formula and explains the timing convention, which distinguishes it from sibling financial tools like internal_rate_of_return and compound_growth.

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 gives clear context for when to use the tool: to compute NPV for a series of periodic cash flows. It does not explicitly name alternatives or state exclusions, but the mathematical definition precisely scopes its application, making the usage unambiguous.

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