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

Annotations already cover the safety profile (read-only, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds genuine behavioral context: the query is parsed for structured conditions, results are sorted low-to-high by monthly fee, and the data source is carrier official homepages (consistent with openWorldHint=false).

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?

Purpose is front-loaded, followed by input behavior, downstream routing to fetch, and examples. Dense but every sentence contributes; the mixed Korean/English phrasing is slightly heavy but appropriate for the bilingual domain.

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 a single required param and no output schema, the description does the needed work: it explains what the free-text query accepts, how results are ordered, and that the returned id feeds fetch for detail and price history. The one gap is not clarifying its relationship to the similarly named sibling search_plans.

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 coverage is already 100% with a one-line '한국어 검색어' description, so baseline is 3. The description earns above baseline by enumerating exactly what the free-text query is parsed for (데이터 GB, 월 요금 상한, 통신망, 5G, 통화 무제한, 통신사, 평생/기간/선착순) plus worked examples, telling the agent how to phrase input.

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 (search) and resource (Korean MVNO 요금제), and adds scope details: it reads conditions from a plain-Korean query and ranks results by lowest monthly fee from carrier official pages. An agent can grasp what it returns, though it never distinguishes itself from the lookalike sibling search_plans, which is a real ambiguity given the near-identical name.

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 routes the agent forward explicitly ('결과의 id 로 fetch 를 부르면 세부 조건·가격 기록이 나옵니다') and gives concrete example queries, which is helpful. However, it gives no when-to-use/when-not guidance against the overlapping siblings search_plans and cheapest_by_data, so usage is only implied.

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