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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds the shape of the result (multiple routes plus a 'best route' and an equivalent PAYE salary) but discloses no defaults, assumptions, or limitations beyond what the schema states.

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 front-loaded sentence that leads with the core transformation and then lists the outputs. It is dense but every clause carries information; the long trailing list of routes makes it slightly run-on.

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 must carry the return-value burden, and it does enumerate the outputs (annual/monthly income, hourly equivalent, take-home pay for three routes, best route, equivalent PAYE salary). It is nearly complete, missing only assumptions and the treatment of optional cost inputs.

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 every parameter including defaults ('defaults to 7.5' hours, tax-year default) is already documented in the schema. The description adds no syntax or format detail beyond it, so the baseline 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 states a specific verb and resource ('turn a contractor day rate into annual and monthly income, an hourly equivalent, and take-home pay') and enumerates the routes covered (sole trader, outside IR35, inside IR35). It never distinguishes itself from siblings like compare_inside_and_outside_ir35 or compare_limited_company_and_sole_trader, which clearly overlap.

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 when-to-use or when-not-to-use guidance, and no alternative is named. Given that compare_inside_and_outside_ir35 and compare_limited_company_and_sole_trader appear to cover the same comparison ground, the absence of routing guidance is a real gap.

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