Almanack

calendar_weekday

Which weekday a date falls on, as a 0-based index into the calendar's own week plus its name. Exact; never estimates. Returns weekday null when the date is an intercalary day the week does not count: those days sit outside the cycle and the week resumes after them exactly where it left off. Fails if the calendar defines no week rather than inventing a seven-day one. Pass 'dates' instead of 'date' for more than one. Answers up to 1000 in one call, in the order given, as {count, ok, results}. Prefer this over one call per item: the spec travels once instead of once each.

Input Schema

TableJSON Schema

Name	Required	Default
`date`	No
`dates`	No
`calendar`	Yes
`on_error`	No	fail

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

Changed7 schema fields changedSep 1, 2026

removedInput schema / properties / date / additionalProperties
```
Removed value: -true
```

addedInput schema / properties / date / anyOf

Added value: +[
+  {
+    "additionalProperties": true,
+    "type": "object"
+  },
+  {
+    "type": "null"
+  }
+]

addedInput schema / properties / date / default
```
Added value: +null
```
removedInput schema / properties / date / type
```
Removed value: -"object"
```

addedInput schema / properties / dates

Added value: +{
+  "anyOf": [
+    {
+      "items": {
+        "additionalProperties": true,
+        "type": "object"
+      },
+      "type": "array"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "title": "Dates"
+}

addedInput schema / properties / on_error

Added value: +{
+  "default": "fail",
+  "title": "On Error",
+  "type": "string"
+}

changedInput schema / required

Previous value: -[
-  "calendar",
-  "date"
-]New value: +[
+  "calendar"
+]

First observedSep 1, 2026

TDQS

A4.5/5.0

Behavior5/5

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

With no annotations provided, the description carries the full burden and does so thoroughly. It discloses exactness, the intercalary-day null return and week-resumption behavior, failure when the calendar defines no week, the 1000-item limit, ordering preservation, and the response envelope {count, ok, results}.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Every sentence earns its place: purpose, edge-case behavior, failure mode, batching, limits, ordering, and output shape are all packed in without fluff. The description is front-loaded with the core meaning and only then adds behavioral details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a focused weekday-lookup tool with no annotations and no output schema, the description is unusually complete. It covers return value semantics, edge cases, error behavior, batch capacity, ordering, response shape, and a usage preference. No critical gap remains for an agent to invoke the tool correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It adds real meaning for date vs dates and the batch limit, and hints at calendar behavior by describing week definition failure. However, it leaves the calendar parameter's structure and the on_error parameter's semantics unexplained, so compensation is only partial.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description immediately states what the tool does: determine which weekday a date falls on, returning a 0-based index and name. It adds precise behavioral distinctions such as exactness, intercalary-day null handling, and failure rather than inventing a week, making it clearly distinguishable from sibling date tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives explicit batching guidance: pass dates instead of date for multiple items, and prefer a single batched call over one call per item. It does not explicitly name sibling alternatives or exclusion cases, but the intended usage context is clear.

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

All Almanack tools Inspect

Try in Browser

RayrunBuild, deploy, and operate MCP servers without becoming an infrastructure team.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

TDQS

A4.2/5.0

Disambiguation5/5

Each tool targets a distinct date/calendar operation: arithmetic, conversion, weekday lookup, period membership, moon phase, daylight, event queries, formatting/parsing, and two different rendering outputs. Even superficially similar tools (calendar_weekday vs nth_weekday_of_month, calendar_events vs calendar_periods) ask clearly different questions that the descriptions make unambiguous.

Naming Consistency4/5

Names are all lowercase snake_case and mostly follow a verb_first or noun_query pattern, but there is a mix: add_to_date, convert_date, and parse_calendar_date are imperative, while moon_phases, sun_daylight, and calendar_events are noun phrases describing what they return. The calendar_ prefix on three tools and consistent rendering parse/format pairs help readability, so this is a minor deviation, not chaos.

Tool Count5/5

15 tools sits at the upper bound of the ideal range for a focused domain toolkit. Every tool addresses a genuine calendar use case (define, convert, query, render, validate, generate), and none feels redundant or extraneous.

Completeness5/5

The set covers the full lifecycle of working with a custom calendar: validation before use, conversion between representations, date arithmetic and intervals, weekday and period queries, recurring events and daylight/moon data, formatting/parsing, and visual rendering. No obvious dead ends or missing operations come to mind for the stated domain.

Resources

Need Help?