四柱排盘（按干支）

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

With no annotations provided, the description carries the full burden. It discloses that the tool reverses the pillars to find possible birth dates and supports multiple candidate results, which is key behavioral context beyond simple mapping. It doesn't cover edge cases or error handling, but for a calculation tool this is acceptable.

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?

Two concise sentences. The first sentence states the trigger condition, the second describes the behavior and output. No wasted words; the example is compact and illustrative.

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?

The tool has moderate complexity (reverse lookup with multiple candidates) and no output schema. The description explains the core outcome (complete chart data, multiple candidates) but doesn't specify the output structure or how many candidates to expect. Still, it's adequate for an AI agent to understand when and why to use it.

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 the schema already documents each parameter. The description adds an example format (甲子年丙寅月戊辰日壬子时) but doesn't clarify how it maps to the separate pillar parameters beyond that. Since the schema does the heavy lifting, the description only marginally enhances parameter understanding.

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?

Description clearly states the tool is called when the user provides the four pillars directly, and uses the specific verb '反推' (reverse-engineer) to explain it infers possible birth dates and returns complete chart data. This distinguishes it from sibling tools like bazi_paipan, which presumably takes a birth date/time.

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 explicitly starts with the condition '用户直接给出四柱干支...时调用' (call when the user directly provides the four pillars), giving clear when-to-use guidance. However, it does not explicitly name alternatives or state when not to use it, leaving the exclusion implicit rather than explicit.

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