Kua Number

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

Annotations already declare read-only, idempotent, closed-world and non-destructive, so the safety profile needs no restating. The description adds genuinely non-structured behavior: the computation basis and, importantly, a per-call cost of 10 credits (Tier 1), which matters when an agent is choosing among hundreds of billed tools. It does not address whether the result is stable across timezones/locales or what errors look like.

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 dense front-loaded sentence conveys function, formula and output meaning; the bracketed metadata lines (group, endpoint, required, cost) are structured facts rather than prose padding. Nothing is wasted, though the group/endpoint lines duplicate indexing info available elsewhere.

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-value explanation is correctly omitted, and annotations cover the safety profile. But for a 7-parameter tool at 29% schema coverage, the omission of how date, solarYear and timezone interact leaves a real ambiguity about correct invocation for births near the solar-term boundary.

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 only 29% — date, time, gender, language and solarYear carry no descriptions — so the description carries a real burden. It does clarify that the year basis is the SOLAR year, which hints at why solarYear exists separately from date, but it leaves the date-vs-solarYear precedence, the timezone/time semantics, and what 'language' affects entirely unexplained.

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+resource: it computes a personal Kua number and states the input basis (solar-year digit sum + gender) and the output's meaning (East/West group for direction work). That is far more than the title alone. However, it never names its closest siblings (astroway_chinese_feng_shui_lucky_directions, bagua, flying_star), so an agent doing 'direction work' could plausibly pick a sibling instead.

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 phrase 'for direction work' implies the downstream use case but gives no explicit when-to-use/when-not or alternative routing — e.g., whether to call lucky_directions directly instead of computing Kua first. Usage is inferable but not stated.

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