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

The description discloses that the calculation is deterministic, side-effect-free, idempotent, and non-destructive, adding behavioral context beyond the annotations. It also documents the edge case of zero invested capital returning 0 and states the output format with rounding behavior.

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-structured with clear labels for definition, usage, behavior, returns, and parameters. Every section carries distinct value and there is minimal redundancy despite the thorough coverage.

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 single-parameter pure calculation tool with no output schema, the description fully covers what the agent needs: formula, sign conventions, edge case, output shape, rounding, and sibling distinctions. No important calling information is missing.

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?

Although the schema already documents cash_flows well, the description adds formula-level semantics: sum of positive cash flows divided by sum of absolute negative cash flows, explicit sign conventions, and a concrete example. This meaningfully supplements the schema.

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 defines MOIC as total distributions divided by total invested, specifies no discounting and no time value, and distinguishes it from related financial metrics. The exact calculation formula makes the tool's purpose unambiguous.

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?

Explicit WHEN TO USE and WHEN NOT TO USE sections state that this tool is for quick money-multiple answers without a discount rate, and it names calculate_irr and calculate_npv as alternatives when time value of money matters. This fully guides tool selection.

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