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

No annotations are present, so the description carries the full burden. It discloses output behavior (year-by-year growth and final interest portion) and the optional verifiable certificate behavior via certify=true. It does not discuss edge cases, but for a calculation tool this is sufficient.

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 three sentences, each adding distinct value: purpose, output explanation, and optional certificate feature. There is slight redundancy with the title in the first sentence, but no unnecessary filler.

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 no output schema and no annotations, the description adequately conveys the tool's function, output nature (year-by-year balance, interest portion), and special feature (certificates). It omits detailed return fields and input format nuances, but for a calculator tool the core info is present.

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 0%, requiring the description to compensate. It clarifies only monthlyContribution and certify, while leaving initialPrincipal, annualRatePct, and years to be inferred from their names. Crucially, it does not specify whether annualRatePct is a percent or decimal, leaving key ambiguity.

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 'Calculate compound interest with monthly contributions,' identifying the exact verb and resource. It also mentions output features (year-by-year balance growth, pure interest breakdown) that distinguish it from sibling calculators.

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 the tool: any compound interest calculation with monthly contributions. However, it does not explicitly mention alternatives or exclusion criteria, so it stops short of full when/not guidance.

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