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

Annotations already establish the safety profile (readOnlyHint, destructiveHint false, openWorldHint false). The description adds domain-meaningful behavior beyond that: it names the statutory basis, the interest rate formula, and the fact that fixed compensation is included in the claim. It does not disclose rounding, the tiered compensation bands, or the minimum claim periods, which would be expected for a statutory calculation.

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-formed sentence that front-loads the calculation and packs the statutory basis, formula, inputs, and purpose without any waste.

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 read-only statutory calculator with full schema coverage and no output schema, the description is largely complete: it names the law, the rate formula, and the three inputs. It omits details that would matter for a correct claim, such as the tiered fixed-compensation amounts and any minimum-days threshold, but the core is present.

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 coverage is 100%, so the three parameters are already documented in the input schema. The description confirms the inputs (amount, due date, payment date) but adds no format, boundary, or default semantics beyond what the schema states. Baseline 3 applies when the schema carries the load.

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 (calculate) plus the exact resource (statutory late-payment interest and fixed compensation on a commercial invoice), names the statutory basis (Late Payment of Commercial Debts Act), and specifies the formula (BoE base rate + 8%). This clearly distinguishes it from siblings like calculate_vat or estimate_self_assessment_penalties.

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 scope is implied by 'late-paid commercial invoice', which implicitly excludes consumer invoices, but there is no explicit when-to-use/when-not-to-use guidance and no named alternatives. Adequate but leaves the agent to infer eligibility boundaries.

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