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

With no annotations, the description carries the burden, and it does disclose two genuinely useful traits: it is a paid endpoint ($0.1 per call) and requires an API key. It also bounds the horizon at 1–12 months. It says nothing about permissions, failure modes, or result shape beyond what the output schema presumably covers.

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?

One sentence for the core behavior plus a compact parenthetical for cost/auth. No filler, and the primary purpose is front-loaded.

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?

Since an output schema exists, return values need not be explained, and the paid/auth constraint is captured. What's missing is disambiguation from siblings and any format expectation for start_date — moderate gaps for a tool whose parameters are schema-undocumented.

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 effectively 0% at the top level: 'months' and 'start_date' have no descriptions. The description compensates partially by defining start_date's role ('시작일부터') and bounding months to 1–12, but gives no format hint for start_date and no default guidance for months.

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?

Names a specific computation ('운세 흐름') and specifies its inputs and outputs: daily/monthly luck interactions (합·충·형·해·파) with the natal chart over 1–12 months from a start date. This distinguishes it from sibling 'monthly' only implicitly — neither description is visible here, so the agent must infer the split.

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?

No statement of when to choose this over 'monthly', 'saju_chart', or 'day_pillar'. The only operational notes are cost ($0.1/회) and API-key requirement, which are constraints rather than usage guidance.

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