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

With no annotations provided, the description carries the disclosure burden. It usefully states the output shape ('Returns yearly values') and the return granularity, plus the compounding default, but says nothing about rate/period conventions, precision, or edge cases (zero years, negative rate).

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 short sentences, front-loaded with the purpose and then the input contract. Every clause earns its place; only the slightly telegraphic input list keeps it from a 5.

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 low-risk pure-computation tool with no output schema, the description gives an adequate contract, but the undocumented locale parameter and unspecified output structure leave gaps an agent cannot fill from structured data.

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%, so the description must compensate. It documents principal, rate (with the 'annual %' unit) and compounds (per year, default 12), which adds real meaning, but it completely omits the locale enum parameter, leaving one of five inputs unexplained.

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 ('Project') and resource ('compound interest') with the key inputs, so the purpose is unambiguous. It does not differentiate itself from the financially adjacent sibling loan-calculator, so it stops short of a 5.

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 use this versus alternatives like loan-calculator, nor any stated prerequisites or exclusions. The agent must infer context from the name alone.

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