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

Annotations (readOnlyHint=false, destructiveHint=false) provide limited safety info. The description adds that the tool returns an API_KEY and must be called first, which is useful behavioral context. However, it does not disclose session lifetime, side effects of creating a session, or how the API_KEY should be used subsequently.

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 description is two sentences with zero filler. The critical sequencing instruction is front-loaded ('Call this FIRST'), followed by the action and return value. Highly efficient.

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 simple login tool, the description covers the essential purpose and ordering, but it does not explain what the API_KEY is used for, how it integrates with other tools, or the session's validity period. Since there is no output schema, the description should carry more explanatory weight.

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 description coverage is 100%, so the parameters are fully documented in the schema. The description adds no parameter-level semantics beyond what the schema already provides, so a baseline of 3 is appropriate.

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 action (login) on a specific resource (FourInsure 4대보험 EDI) and names its return value (API_KEY). It also distinguishes this tool from sibling login tools for other providers by explicitly naming FourInsure and saying 'for this provider'.

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 clearly states when to use this tool: 'Call this FIRST before any other tool for this provider.' This gives a clear sequencing context. It does not explicitly mention alternatives for other providers, but that is implied by 'for this provider' and the sibling names.

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