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

The description discloses that the tool is paid ($0.10), requires an api_key for full usage, and explains that schemes that cannot be priced will appear in a 'refused list' rather than being silently zero. However, it does not mention other potential behaviors like error handling, rate limits, or side effects beyond cost and refusal lists.

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 concise and packed with essential information in two sentences. It covers the core function, output specifics, exclusions, and payment handling without any redundancy. The structure is efficient and immediately actionable.

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?

Given the lack of an output schema, the description adequately describes the return (line-by-line amounts, citations, refused list). It also clarifies what the tool does not do (income tax). While it could elaborate further on the computation logic or edge cases, the description provides sufficient context for an agent to decide on invocation.

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?

All 11 parameters have descriptions in the schema, achieving 100% coverage. Each description provides meaningful context (e.g., 'Germany care surcharge', 'Auto-enrolment / PPK participation'), going beyond mere labels. While some descriptions are terse, they collectively define each parameter's role clearly.

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 states the tool computes employment cost (statutory contributions) for a gross salary, breaking down employee and employer sides. It explicitly distinguishes itself from income tax calculation by pointing to compute_payroll, ensuring the purpose is unambiguous.

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 provides direct guidance on when to use this tool versus alternatives (e.g., 'Does NOT compute income tax — use compute_payroll'). It also instructs on passing an api_key and what happens if it's not provided, giving clear usage direction.

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