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

Annotations only tell us this is a non-read-only, non-destructive call, so the description adds real value by disclosing a per-call cost ('호출마다 토큰 1소진') and the retry/recovery semantics of request_idempotency_key, including the warning that an omitted key makes a repeat call a genuinely new request. It does not cover session lifetime or what credentials/permissions the account link must satisfy.

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 leading and trailing sentences (ordering rule, token cost) are high-value, but the middle is a long generic idempotency boilerplate block, and the phrase 'anonymous taste calls' is unexplained jargon that costs attention without informing the call. Mixed-language output also breaks the otherwise clean front-loading.

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 zero-required-parameter login tool with no output schema, the description covers the essentials: when to call, what it establishes, cost, and the idempotency contract. Session persistence and post-login state are left implicit, which is a modest but real gap for an auth entry point.

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 100%, so all three parameters are already documented, but the schema explicitly defers idempotency semantics to the description ('see the tool description') and the description delivers them, including the crucial disambiguation from a provider-specific idempotency_key field. auth_provider and account_link_id get no extra meaning beyond the schema, keeping this below a 5.

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 second sentence states a specific verb and resource — 'Create a KB Biz Card certificate/NPKI session from a registered account link' — which is unambiguous and provider-scoped. It is clearly the entry point of the kb_biz_card family, though the differentiation from the many other provider login siblings rests on the 'this provider' phrasing rather than an explicit contrast.

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?

'Call this FIRST before any other tool for this provider' gives an unambiguous ordering rule, and the idempotency-key paragraph spells out exactly when to reuse a key versus mint a new one. What is missing is any exclusion: it never says what to do if a session already exists or how long the session remains valid.

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