Four Pillars (full)

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

Beyond the annotations (readOnlyHint, idempotentHint), the description adds important behavioral context: the specific day pillar algorithm, requirement for 'time' parameter, and the 23:00 CST day-shift handling with timezoneOffset. This significantly aids understanding beyond the structured fields.

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 highly concise—two focused sentences plus a group label and example. Every sentence adds essential information without redundancy, and the structure front-loads the core purpose.

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?

Given no output schema, the description does not specify the return structure, and it omits explanation of latitude/longitude parameters, which are present in the schema. For a tool with four parameters, this leaves some contextual gaps for an AI agent.

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?

While input schema descriptions cover parameter formats, the description adds semantic value by explaining how 'time' and 'timezoneOffset' jointly compute the hour pillar and handle day-shift, and provides an example, enriching the schema-provided info.

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 clearly states that the tool returns all four BaZi pillars (year, month, day, hour), specifies the day pillar calculation method (HKO-canonical 60-jiazi cycle), and distinguishes from sibling tools that return only individual pillars or other aspects.

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 implies usage when the full set of four pillars is needed, but does not provide explicit when-to-use, when-not-to-use, or alternatives, leaving the agent to infer context from the name and sibling list.

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