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

Annotations already declare this as a safe, read-only, closed-world calculation, so the safety profile is covered. The description adds useful substance by disclosing the calculation order (employer NI and corporation tax come off before dividends are paid) and that all taxes plus an effective rate are returned. It does not mention anything about assumptions, limits, or defaults beyond what the schema shows.

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 dense sentence that front-loads the audience and the core computation before the deduction detail. Every clause carries information, though the sentence is long enough that the 'compare' aspect of the tool name is never resolved.

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?

With no output schema, the description carries the return-value burden and does so adequately by promising every tax plus the effective rate. For a 3-parameter pure calculation, the definition covers what is computed and from what inputs; only the comparative/optimization intent hinted at by the name is left unexplained.

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 all three parameters are already documented, and the baseline is 3. The description adds marginal value by clarifying that the profit figure is consumed after employer NI and corporation tax and that dividends come from the remainder, but it gives no units, precision, or default guidance beyond the schema.

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 names a specific computation (take-home pay from salary plus dividends), the audience that scopes it (limited company director), and the deductions included (employer National Insurance, corporation tax). It is clearly distinguishable from generic siblings like calculate_take_home_pay or calculate_dividend_tax, though it never names those siblings or explains the 'compare' framing implied by the tool name.

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?

Usage is only implied through the audience qualifier 'For a limited company director', which implicitly excludes employee/sole-trader cases handled by siblings. There is no explicit when-to-use statement and no routing to alternatives such as compare_limited_company_and_sole_trader or calculate_salary_sacrifice.

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