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

Annotations already declare readOnlyHint and idempotentHint, so the description's claim of '确定性' results is a useful corroboration rather than new information. It does add real behavioral context beyond annotations: the subject must never be fabricated and must be normalized and confirmed before calling. It does not discuss failure modes or what happens on out-of-range input, which keeps it below a 5.

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?

Front-loaded with the verb and result, then the subject sourcing rule, then the call trigger, then the sibling disambiguations. The long enumeration of star categories and deity sets is dense but each item earns its place as a call trigger. Slightly heavy for a single description but no filler sentences.

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?

An output schema exists, so return values need not be explained, and the description still signals that output is deterministic palace facts. With a single nested required parameter, 100% schema coverage, and clear routing to the three relevant siblings, an agent has everything needed to invoke this correctly.

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% with nested field descriptions, so the baseline is 3. The description goes further by explaining where the subject values legitimately come from (user-stated facts or confirmed subject_candidates) and by mandating normalization and confirmation when the time is ambiguous, which is procedural meaning the schema does not encode.

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?

States a specific verb and resource (紫微斗数排本命盘) plus what it returns (确定性宫位事实), then names the sibling tools it is not: ziwei_bond for composite charts, ziwei_liupan for transit charts, natal_query for combined Bazi-Ziwei readings. An agent can route between these without opening any schema.

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?

Gives an explicit call trigger (when the user needs 十二宫主星, 亮度, 四化, 杂曜, 长生博士十二神, 小限 or 大限) and explicit alternatives with their selecting conditions. It also describes the prerequisite workflow: assemble subject from stated facts or from user-confirmed subject_candidates, and normalize/confirm when the time is fuzzy or candidates are multiple.

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