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

With no annotations, the description must disclose behavior itself. It usefully reveals that the calculation is broken down by NBP reference-rate periods, which is non-obvious. However, it does not describe the return format or any edge-case behavior, though for a pure calculation tool this is a moderate gap.

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?

A single, well-structured sentence that front-loads the core purpose and then adds the key behavioral detail. Every word earns its place and there is no redundancy.

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 tool is a focused calculation with four fully documented required parameters and no output schema. The description plus schema provides enough context for an agent to invoke it correctly; a return-format hint would be the only meaningful addition.

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 100%, and the schema documents each parameter thoroughly, including the typ enum and date formats. The description adds no new parameter-level meaning, so the baseline score of 3 applies.

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 uses a specific verb ('Calculate') and names the exact resource: statutory or commercial (B2B) late-payment interest. It also adds the distinctive behavioral detail of being 'broken down by NBP reference-rate periods', which clearly separates it from the unrelated sibling tools.

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 makes the use case clear: calculating statutory or commercial late-payment interest. It does not explicitly state when not to use it or name alternatives, but no sibling tool performs this function, so the absence of exclusions is acceptable.

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