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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful behavior beyond annotations: it will explicitly report when there is no reserved seat, and it requires a LIBRARY-authenticated session.

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?

Three short sentences front-load the core purpose, then add the empty-result behavior, alternatives, and session requirement. No filler; each sentence earns its place.

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 read-only, single-optional-parameter lookup, the description covers what the tool does, the no-result case, the session prerequisite, and relevant action alternatives. It does not enumerate returned fields, and there is no output schema, but the level of detail is sufficient for correct selection and invocation.

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?

The input schema already documents mcp_session_id as optional with a bound-session fallback (100% coverage), so the baseline is 3. The description adds the LIBRARY-login auth requirement, which clarifies what kind of session is needed beyond the schema text. The wording '필요' is slightly looser than the schema's optional flag, but the intended meaning is clear.

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 ('조회합니다' / retrieves) and a specific resource: the currently reserved library seat. It also covers the empty-result behavior ('no reserved seat -> says none') and explicitly names the sibling tools for canceling and swapping, so an agent can distinguish the query action from follow-up mutations.

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?

It tells the agent exactly when to use this tool: to check the current reserved seat, and explicitly routes to prepare_cancel_library_seat for returning and prepare_swap_library_seat for changing seats. It also states the LIBRARY-login session prerequisite, which is key context for selecting this tool successfully.

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