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

With no annotations, the description carries the behavioral burden, and it does disclose that the tool produces four specific annual facility-cost metrics. It also discloses fallback-to-default behavior for missing inputs. It does not explicitly state read-only or no-side-effect behavior, but 'calculate' plus the output list makes that a reasonable inference.

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 with the action, and the semicolon-separated output list is efficient. However, the redundant 'calculator calculator' typo reduces polish, and the description could be cleaner while staying concise.

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 calculator with no output schema, the description lists the main computed values and mentions default fallback, which covers the essentials. It does not show how the seven inputs map into the calculation or describe any output formatting, so an agent still relies on the schema for parameter semantics.

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%, so the baseline is 3 and the description does not need to restate parameter meanings. The only parameter-related addition is the default fallback note, which is useful operationally but adds no meaning beyond the schema's documented defaults.

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 concrete action ('Run the Invoice factoring cost calculator') and enumerates the computed metrics: service fee for the year, average balance drawn, discount charge, and total annual cost. This makes the tool's purpose clear, though it does not explicitly differentiate from siblings and includes the awkward 'calculator calculator' wording.

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 when-to-use or when-not-to-use guidance versus siblings like calculator_describe. The only usage-related statement is 'Missing inputs fall back to their documented defaults,' which is helpful for calling the tool but does not address tool selection; the intended usage is mostly implied by the title and tool name.

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