The nth given weekday of a month: the 3rd Tuesday, the last Friday. n is 1-based from the start of the month, or negative from the end (-1 is the last). Only days the week counts are considered. If the month has no such day the call fails naming how many there are; it never returns the nearest one instead. Exact; never estimates.
| Name | Required | Description | Default |
|---|---|---|---|
| n | Yes | ||
| year | Yes | ||
| month | Yes | ||
| weekday | Yes | ||
| calendar | Yes |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly states that n is 1-based or negative, that failure occurs when the month lacks such a day, that the call reports how many such days exist, and that it never returns the nearest match. The 'Exact; never estimates' statement adds further clarity about deterministic behavior.
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 description is appropriately short and front-loads the core concept with examples. Every sentence contributes useful information, though the phrase 'Only days the week counts are considered' is awkward and may confuse rather than clarify the counting rule.
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?
For a pure date calculation, the core algorithm and failure behavior are well covered. However, with no output schema and a nested calendar parameter, the description does not explain the expected return value or how to construct/interpret the calendar object, leaving the tool incompletely specified for an agent.
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?
The description thoroughly explains the n parameter (1-based from start, negative from end) and gives examples for weekday. However, schema description coverage is 0%, and the calendar, year, month, and weekday encoding are left undefined. The nested calendar object in particular receives no explanation, leaving a significant semantic gap.
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 clearly states that the tool computes the nth occurrence of a given weekday in a month, with concrete examples ('the 3rd Tuesday, the last Friday'). It differentiates itself from sibling calendar tools by specifying exact weekday-ordinal semantics, though it lacks an explicit verb like 'returns' or 'computes'.
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 description explains the calculation semantics but provides no guidance on when to use this tool versus alternatives such as calendar_weekday, date_interval, or convert_date. There are no exclusions or contextual conditions, so an agent must infer usage from the tool name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each tool targets a distinct calendar operation, and the descriptions carefully draw boundaries between related concepts. There is modest overlap: convert_date also reports a named period, and calendar_events can answer nth-weekday questions that overlap with nth_weekday_of_month, so an agent might occasionally pick the wrong entry point.
All names are readable and consistently snake_case, but the set mixes verb-led names like convert_date and render_timeline with noun-led names like calendar_events and moon_phases, plus one prepositional verb in add_to_date. This is a readable mixture rather than a uniform verb_noun pattern.
Fifteen tools sits at the upper end of the typical well-scoped range, but every tool fills a distinct role for an almanac-style server: date math, conversion, calendar queries, formatting, parsing, rendering, lunar and solar calculations, generation, and validation. The batched plural parameters also make the count feel intentional rather than bloated.
The surface covers the domain unusually well: conversion, arithmetic, events, periods, weekdays, format/parse, SVG rendering, moon phases, daylight, scattering, and validation all have dedicated tools. The main gap is introspection—there is no direct way to list a calendar spec's months, eras, week structure, periods, or formats beyond what other tools reveal through errors and outputs.