compound_interest

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

The description adds valuable behavioral context beyond the readOnlyHint annotation by specifying what the tool outputs ('final value, total contributions, total interest earned, and a year-by-year growth table') and mentioning the 'standard compound interest formula with optional periodic contributions'. This provides useful information about the tool's behavior that isn't captured in the annotation alone.

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 perfectly structured with two concise paragraphs. The first sentence immediately states the core purpose, and subsequent sentences efficiently elaborate on outputs and methodology. Every sentence earns its place with no redundant 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?

Given the tool's moderate complexity, 100% schema description coverage, readOnlyHint annotation, and the existence of an output schema, the description is complete enough. It explains what the tool does, what it outputs, and the methodology used, which is sufficient when combined with the well-documented structured fields.

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?

With 100% schema description coverage, the input schema already provides comprehensive parameter documentation. The description adds minimal semantic value beyond what's in the schema - it mentions 'optional regular contributions' which relates to the monthly_contribution parameter, but doesn't provide additional context about parameter interactions or usage patterns.

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 states the tool's purpose with specific verbs ('project investment growth', 'shows final value') and resources (compound interest calculations). It distinguishes from sibling tools like 'debt_payoff_plan' and 'mortgage_calculator' by focusing specifically on investment growth projection rather than debt or loan scenarios.

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 clear context for when to use this tool ('project investment growth with compound interest and optional regular contributions'), but doesn't explicitly state when NOT to use it or name specific alternatives among the sibling tools. The context is sufficient to understand this is for investment growth projection rather than debt or loan calculations.

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