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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, openWorldHint=false), lowering the bar. The description adds useful output disclosure — total ROI, net profit, annualized rate — which matters because there is no output schema, but it omits edge behavior such as how a missing/default 'years' affects the annualized result.

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?

Three tight sentences with zero waste, though the lead is a worked example rather than the purpose statement, which slightly delays the front-loaded 'what it does' information.

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 zero-required-parameter calculator with no output schema, the description does state what is produced and gives a concrete example, making it callable without opening the schema. It is only missing any steering toward sibling tools on overlapping concepts.

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 description coverage is 100%, so all four parameters are already documented (including 'years' being required for annualized ROI). The example maps loosely onto invested/returned/years but adds no syntax or format meaning beyond the schema, so the baseline 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?

States a specific verb+resource: it computes total ROI, net profit and annualized rate, illustrated with a worked example ($10k → $15k = 50%). However, it does not distinguish itself from near-siblings like cagr_calculator, profit_margin_calculator or future_value_calculator, so an agent must infer the boundary.

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 contains no when-to-use, when-not-to-use, or alternative-tool guidance, which matters in a catalog of 150+ calculators with several overlapping finance tools. Usage is only implied by the example.

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