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

With no annotations, the description must carry the behavioral load. It does not disclose the conversion formula (simple multiplication vs. compounding), input format (percentage vs. decimal), rounding, or output shape, all of which materially affect correct use.

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 short and front-loaded, but the phrase 'Monthly To Annual: Convert monthly to annual' largely restates the tool name without adding information. It avoids bloat but wastes an opportunity to clarify.

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 tool with no output schema and no annotations, the description is too thin: it does not explain the result (e.g., rate*12 vs. compound annualization), leaving the agent unable to invoke it confidently or interpret output.

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?

The schema fully documents the single 'rate' parameter (100% coverage), so the baseline is 3. The description adds no meaning beyond the schema, not clarifying whether 'rate' is a percentage, decimal, or annualized value.

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 states a clear operation direction ('Convert monthly to annual'), but it does not specify what is being converted (rate? return?) or add sibling differentiation beyond the tool name itself. It is more specific than a bare name, but still vague about the domain.

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?

No guidance is given on when to use this tool versus alternatives such as x402-annualized-return or x402-compound-interest. The description provides only a bare statement of operation, leaving context selection entirely to the agent.

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