Compound interest / savings growth

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is clear. The description adds useful behavioral context beyond annotations: it lists the return values (final balance, total deposits, interest earned, year-by-year table) and states domain constraints (rate –50–100%, 1 month to 100 years).

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 front-loaded with the tool's purpose and remains dense with useful details. The first sentence is long but well-structured, and the subsequent sentences cover returns, constraints, and a web reference without excessive verbosity.

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?

With 8 parameters, no output schema, and rich schema descriptions, the description adequately explains the calculation model, return values, and key constraints. It could be slightly more complete by noting edge cases or the effect of table=false, but it is sufficient for correct invocation.

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 coverage is 100%, so parameter documentation is already strong. The description adds semantic meaning beyond the schema: it clarifies contribution timing (start or end of month), the interpretation of inflation as "today's money," and rate/duration bounds, which help an agent reason about the calculation.

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 a specific verb ("Project savings") and clearly states the resource and mechanics (compound interest with initial deposit and monthly contributions). It distinguishes itself from siblings like calc_loan and calc_salary by focusing on savings growth with contributions and compounding options.

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 implies the tool's use case (projecting savings with compound interest), but it does not explicitly state when to use this tool versus alternatives such as calc_loan or calc_discount. No exclusions or conditional guidance are provided, leaving the agent to infer the appropriate context.

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