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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful output context (final balance, total contributed, interest earned), but it does not disclose calculation assumptions such as contribution timing or compounding behavior beyond what the schema states.

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 a single front-loaded sentence with no wasted language. It efficiently states the tool's purpose, optional variant, and return values.

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?

The description names the returned values, which is helpful because there is no output schema. However, with five parameters and only 40% schema description coverage, it leaves relevant invocation details such as contribution timing and compounding assumptions unaddressed.

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 only 40%, and the description adds meaning only for the optional monthly contribution. It does not explain principal, annual_rate_percent, years, or compounds_per_year beyond what their names and the two schema descriptions already convey.

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 identifies a compound-interest calculator and names the optional monthly-contribution variant, along with the outputs it produces. It is specific enough to distinguish this from sibling tools like calculate_percentage or convert_units, though it does not explicitly contrast with alternatives.

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 explicit guidance on when to use this tool versus another, nor any stated prerequisites or exclusions. Usage is only implied by the tool name and the mention of optional monthly contributions.

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