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

readOnlyHint already covers the safety profile, so the bar is lower; the description still earns credit by disclosing the response contents — the department's parent and children — which is real behavioral information not in any structured field. It omits edge behavior such as what happens with an unknown id or whether child expansion is bounded, keeping it short of a 5.

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 clause, front-loaded with the verb and resource, with the return shape appended. Nothing to trim and nothing buried.

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 one-parameter read tool with annotations covering safety and no output schema, the description supplies enough: what it returns and how to identify the record. Minor gaps remain around missing-id behavior and whether the children list is complete or truncated.

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?

Only one parameter, and the schema already documents it at 100% coverage, including the provenance hint ('from smarthr_list_departments'). The description's 'by id' adds nothing the schema does not already supply, 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?

States a specific verb and resource ('Get one department by id') and even names the returned shape (parent and children), plus the Japanese term 部署. The singular 'by id' framing distinguishes it cleanly from smarthr_list_departments without needing the schema.

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 'by id' phrasing implies this is the detail-fetch counterpart to the list tool, but no alternative is named and no when-not guidance or prerequisite is given. Usage is inferable rather than explicit.

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