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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds real behavioral detail beyond them: it returns an error above 20M gross revenue, computes without deduction and sets a flag when other_comprehensive_income is omitted, and apportions mixed registered/unregistered cases by revenue ratio.

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?

Front-loaded English summary followed by structured Korean rules; each sentence carries real content. The English sentence partially restates the title, and the bilingual format introduces mild redundancy, but nothing is filler.

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 4-param calculator with no output schema and complete annotation coverage, the description supplies the critical computation rules and error/missing-input behavior. It does not describe the return shape or the tax_reduction parameter, which keeps it just short of fully complete.

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?

With 0% schema description coverage, the description must carry the param burden and largely does: it explains registered_revenue/unregistered_revenue apportionment, the role of other_comprehensive_income in gating deductions, and the deduction/expense rates. tax_reduction is left entirely unexplained, so there is one clear gap.

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+resource with scope: computes the 14% separate tax on residential rental income up to 20 million won. It is clear this is the calculation tool, but it never explicitly contrasts itself with the close sibling judge_rental_income_tax (eligibility judgment), leaving the boundary to inference.

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?

Clearly states applicability conditions: deductions apply only when other_comprehensive_income is ≤ 20M, and it returns an error when gross revenue exceeds 20M (out of scope for separate taxation). No alternative tool is named for the eligibility/other-income cases, so it stops short of full when-not/alternatives guidance.

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