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

With no annotations, the description carries the full burden and does disclose non-obvious traits: determinism, valid range 1900-2100, public/local/no API key, and output-time constraints (no invented pillars, no fortune claims, no marriage/burial/god directions). It still does not describe response shape or failure modes, but the behavioral disclosure is well above average.

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 core purpose is front-loaded, but the body is a sprawling comma-separated trigger list mixed with partial-sentence prohibitions, and the 'not 宜忌/吉凶' warning is repeated in two different forms. Functional but not tight.

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?

There is no output schema, so the description correctly compensates by summarizing the return (lunar + ganzhi, then body/work/plan lanes). Combined with the stated date range, default timezone, and no-auth/local operation, an agent has enough to call it correctly; only return-format granularity is missing.

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% and all three parameters (date, hour, locale) are already documented in the schema, including the default and range the description repeats. The description adds no syntax, edge-case, or interaction detail (e.g., how hour interacts with the day pillar) beyond what the schema states, so the baseline 3 applies.

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 concrete resource (Chinese almanac / lunar + ganzhi data for a civil date) and a specific behavior (deterministic rules engine, same day -> same answer). The trigger phrases (黄历, tong shu, lunar date, day pillar) make its domain legible, though it never names which sibling (solar_terms, personal_day, today_rhythm) it should be chosen over.

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?

Provides a rich 'call when the user asks...' list covering 黄历/宜忌/lunar date/day pillar/zodiac/solar term style requests, which is clear positive routing guidance. It states what the tool must NOT be read as (宜忌/lucky-day/吉凶), but that is an interpretation guardrail rather than an explicit sibling alternative, so it stops short of full when/when-not routing.

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