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

Annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds a genuinely decision-relevant behavior the annotations do not: the 10-credit Tier 1 cost per call, plus the grouping. It stops short of describing what the response contains, but an output schema exists to cover that.

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 compact lines with the core concept front-loaded and no filler. It is terse rather than padded; the brevity is a virtue here even though the content itself is thin.

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 output schema and annotations relieve the description of return-value and safety duties, and the domain framing (G1–G9, spiritual influence per night) is reasonably rich. What remains missing is the operational core — what calling this with a date yields and how it differs from sibling Mayan tools — which is the minimum an agent needs.

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 67% and the single REQUIRED parameter, `date`, has only a regex pattern with no description at all — the description never clarifies whether it is a Gregorian calendar date, a birth date, or a Mayan date. With the most important parameter undocumented in both places and 0% of the description devoted to inputs, the description fails to compensate.

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 names a specific domain concept — the 9-day cycle of underworld deities G1–G9 ruling each night — but never states what the tool actually does with the required date (compute the Lord of the Night for that date? list the cycle?). It also gives no signal to separate it from Mayan siblings like astroway_mayan_tzolkin, astroway_mayan_dreamspell, or astroway_mayan_haab.

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?

No when-to-use guidance, no prerequisites, and no routing to or away from any of the seven other Mayan tools in the sibling list. The only operational cue is the [Group: Mayan Calendars] tag, which is categorization rather than usage direction.

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