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

Annotations already provide readOnlyHint=false, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable context: deterministic behavior (matching idempotency), citation of primary sources (supporting open-world), and a billing guarantee that errors/unverified rules are never billed. This goes beyond what annotations convey and clarifies cost and correctness expectations.

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 two concise sentences with zero filler. The purpose is front-loaded, followed by pricing and behavioral notes. Every clause adds value, and it is appropriately sized for the tool's complexity.

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 tool with 6 parameters (including a nested payslip object) and no output schema, the description provides a clear overview of the audit process and output verdicts (match/explainable/mismatch). It mentions pricing and determinism, but does not detail the full output structure or edge cases. Given the complete parameter schema and the core behavior explained, this is adequate but not exhaustive.

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 has a description in the schema. The tool description does not add parameter-specific meaning beyond the schema; it mentions 'recompute statutory premiums and withholding tax' which indirectly relates to parameters like prefecture and age, but does not elaborate. Baseline 3 is appropriate given full schema coverage.

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 ('Audit'), a clear resource ('a Japanese payslip'), and the exact outcome (recompute premiums/tax and diff with per-item verdicts). It also adds pricing and determinism, which helps distinguish it from sibling payroll tools that compute rather than audit.

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 implies usage: when you have a Japanese payslip to audit. However, it does not explicitly mention when not to use it, nor does it name any alternative sibling tools like jp_payroll_net or jp_social_insurance. The guidance is inferred from the purpose rather than stated directly.

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