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

With no annotations, the description carries the full transparency burden. It fully discloses the calculation formula and the sign/index convention for cash flows, which is strong behavioral transparency. However, it does not mention edge cases, rate period assumptions, or how currency affects the output.

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?

Two sentences pack the formula and the critical period-0 convention with zero redundancy. Every element earns its place.

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?

For a simple calculation, the core math and a key input convention are covered, but the missing semantics for 'currency' and lack of any stated return value leave gaps, especially since there is no output schema.

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 schema has 0% description coverage, so the description must compensate. It explains cashflows indexing and rate's role in the formula, but the currency parameter is entirely unexplained, leaving a gap in parameter semantics.

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 via the explicit discounted cash flow formula, which distinguishes it from siblings like internal_rate_of_return and compound_growth. The formula and cashflows[0] convention make the tool's purpose unmistakable.

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 an important usage constraint by noting cashflows[0] is period 0 (usually the negative outlay), but it does not state when to prefer NPV over alternatives like IRR or compound growth, nor any exclusions or prerequisites.

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