npv

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states the basic function and does not disclose conventions such as sign handling (e.g., negative cash flows as outflows), period alignment, or how the output is presented. The description adds no behavioral details beyond what the schema already specifies.

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 a single sentence of 10 words, front-loaded with the action and object. Every word contributes to the core function, with no redundancy or extraneous detail.

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 simplicity, two fully described parameters, and the presence of an output schema, the description is minimally sufficient. The schema covers parameter semantics and the output schema handles return value description, so this is not critically incomplete—though it lacks usage context and behavioral caveats that would be expected for an unannotated tool.

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 comprehensive descriptions for both parameters: cash_flows includes 'index 0 is t=0' and discount_rate includes 'as a percentage', yielding 100% schema_description_coverage. The description does not add any parameter-specific meaning beyond restating 'series of cash flows', so the baseline of 3 applies.

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 the specific verb 'Calculate' and identifies the resource 'Net Present Value of a series of cash flows', clearly distinguishing it from sibling financial tools like irr or loan_comparison. The scope is explicit and unambiguous, making the tool's primary function immediately apparent.

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 provides no guidance on when to use this tool versus alternatives such as irr, financial_calc, or investment_scenarios. It simply states the calculation without any context, exclusions, or reference to related tools, leaving the agent without direction for tool selection.

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