Tzolkin Day Sign

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely useful context beyond them — the 10-credit Tier 1 cost and the exact fields returned — but says nothing about input validation failures or how the date maps to a sign.

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-loads what the calendar is and what comes back, then the endpoint/cost/required lines. The bracketed metadata is templated but functional; nothing is redundant or padded.

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?

With an output schema present, the return-value summary plus the credit cost and required-parameter note give an agent enough to call a low-complexity single-parameter lookup correctly. The only real gap is date format/semantics, which the schema's regex partly covers.

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 0% and the single parameter is undocumented in the schema. The description only repeats '[Required: date]' without clarifying that the format is YYYY-MM-DD, whether the date is Gregorian or Julian, or whether time/timezone affects the result — a real ambiguity for calendrical tools.

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: computes the Tzolkin (260-day sacred calendar) day sign, and enumerates the returned components (1-13 number, day-name, element, direction, keyword). The Mayan terminology implicitly separates it from the Haab/Long Count siblings, but no sibling is named explicitly.

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?

Usage is only implied: pass a date to get its day sign. There is no guidance on when to prefer this over astroway_mayan_haab, astroway_mayan_long_count, astroway_mayan_calendar_round, or astroway_mayan_full, nor any prerequisite or exclusion statement.

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