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

With no annotations, the description carries the full burden. It usefully discloses the x402 payment model and exact price ($0.001/call, USDC on Base), which is real behavioral context, and defines the returned quantities. It does not, however, state error behavior (e.g., what happens if initial=0) or latency/payment-failure handling.

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 front-loaded sentences: the computation first, then pricing set off by an em dash. Little waste, though the pricing detail could arguably sit in a separate cost field.

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 two-parameter compute tool with no output schema, the description supplies the semantics of both results (profit/loss and percentage) plus cost per call, which is enough to invoke it correctly. Only payment-error and edge-case behavior are 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?

Schema description coverage is 100% and both parameters are documented there as 'Amount invested' and 'Final value'. The description's phrase 'relative to the initial amount invested' only echoes the schema, adding no new syntax or constraint information, 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 ('calculate') and resource ('return on investment') and spells out the two outputs: profit/loss and percentage return. This clearly separates it from siblings like finance_cagr_calculator and finance_margin_calculator, which compute different financial ratios.

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?

There is no guidance on when to choose this tool over the other finance calculators, and no mention of prerequisites such as needing a funded x402 wallet. The agent must infer usage purely from the name and formula description.

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