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

Annotations already declare non-read-only, non-destructive, non-idempotent, so the safety profile is covered. The description adds the crucial non-obvious trait that this tool does not actually change the number — the user completes SMS verification and application in the screen, and no verification code is received here — which prevents an agent from believing the change is applied after this call.

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 English lead sentence is front-loaded and efficient, but the Korean text restates the same purpose before adding new information, so part of the body is redundant for a bilingual reader. Nothing is badly bloated, but a sentence is doing work twice.

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 no-output-schema tool, the description says what screen gets opened and that the tool does not mutate anything, which is the key context. It is silent on what the agent should do with the result (present it to the user?) and how it connects to get_contact_change_status or apply_consultation_change afterward, leaving the flow incomplete.

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 only 33% (only phone is documented), but the description compensates for the most important gap by explaining what purpose=default and purpose=request mean in user-visible terms. request_id remains unexplained in both schema and description, so the description does not fully close the coverage 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?

The English opener states a specific verb and resource (open verification for changing contact) and the Korean text clarifies the two scopes: purpose=default for future consultations, purpose=request for one pending consultation. This meaningfully separates the tool from begin_contact_verification and get_contact_change_status, though no sibling is named explicitly.

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?

"이용자가 연락받을 번호를 바꾸고 싶을 때" plus "먼저 둘 중 무엇인지 한 번 확인한 뒤 호출하세요" gives a clear trigger and a pre-call decision step for the two purpose values. It stops short of naming alternatives or when-not-to-use cases (e.g., versus begin_contact_verification or apply_consultation_change).

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