Crystals MCP Server by RoxyAPI

Daily crystal - Crystal of the day API

post_crystals_daily

Read-only

Get the crystal of the day as a discovery teaser. Returns a deterministic crystal based on the current date (or a provided seed date), ensuring all users see the same crystal for any given day. Use the /crystals/{id} detail endpoint for complete spiritual, emotional, and physical healing properties. Perfect for daily guidance features, push notifications, wellness app widgets, and crystal journal integrations.

Input Schema

Name	Required	Description	Default
`date`	No	Date for the reading in YYYY-MM-DD format. Defaults to today (UTC). Useful for viewing past daily readings or pre-generating future ones.
`lang`	No	Response language (BCP 47). Supported: en, tr, de, es, hi, pt, fr, ru, zh-Hans, zh-Hant. Defaults to en. Coverage varies by domain, and a field with no translation in the requested language returns English.	en
`seed`	No	Optional seed for reproducible readings. Same seed + same date = same crystal every time. Pass any unique identifier (userId, email hash, session token) to give each user their own crystal for the day. Without a seed every caller receives the same shared crystal of the day.
`compact`	No	Set true for the same data in a compact shape: arrays of same-shaped objects arrive columnar as {"__cols":[names],"__rows":[[values]]}. Lossless, typically 40 to 52 percent fewer tokens.

Output Schema

Name	Required	Description	Default
`id`	Yes
`date`	Yes
`name`	Yes
`seed`	Yes
`chakras`	Yes
`imageUrl`	Yes
`affirmation`	Yes
`description`	Yes
`zodiacSigns`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 22, 2026

changedInput schema / properties / seed / description

Previous value: -"Optional seed for reproducible readings. Same seed + same date = same crystal every time. Pass any unique identifier (userId, email hash, session token). Omit for anonymous daily readings."New value: +"Optional seed for reproducible readings. Same seed + same date = same crystal every time. Pass any unique identifier (userId, email hash, session token) to give each user their own crystal for the day. Without a seed every caller receives the same shared crystal of the day."

Changed1 schema field changedSep 20, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "affirmation": {
+      "type": "string"
+    },
+    "chakras": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "date": {
+      "type": "string"
+    },
+    "description": {
+      "type": "string"
+    },
+    "id": {
+      "type": "string"
+    },
+    "imageUrl": {
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "name": {
+      "type": "string"
+    },
+    "seed": {
+      "type": "string"
+    },
+    "zodiacSigns": {
+      "items": {
+        "type": "string"
+      },
+      "type": [
+        "array",
+        "null"
+      ]
+    }
+  },
+  "required": [
+    "date",
+    "seed",
+    "name",
+    "id",
+    "imageUrl",
+    "description",
+    "chakras",
+    "zodiacSigns",
+    "affirmation"
+  ],
+  "type": "object"
+}

Changed2 schema fields changedAug 25, 2026

changedInput schema / properties / lang / description

Previous value: -"Response language (ISO 639-1). Supported: en, tr, de, es, hi, pt, fr, ru. Defaults to en. Languages without translations yet return English."New value: +"Response language (BCP 47). Supported: en, tr, de, es, hi, pt, fr, ru, zh-Hans, zh-Hant. Defaults to en. Coverage varies by domain, and a field with no translation in the requested language returns English."

changedInput schema / properties / lang / enum

Previous value: -[
-  "en",
-  "tr",
-  "de",
-  "es",
-  "hi",
-  "pt",
-  "fr",
-  "ru"
-]New value: +[
+  "en",
+  "tr",
+  "de",
+  "es",
+  "hi",
+  "pt",
+  "fr",
+  "ru",
+  "zh-Hans",
+  "zh-Hant"
+]

Changed2 schema fields changedAug 17, 2026

addedInput schema / examples
```
Added value: +[
+  {}
+]
```

changedInput schema / properties / compact / description

Previous value: -"Set true to receive the exact same data in a token-optimized shape that is cheaper for you to read: whitespace is stripped and every array of same-shaped objects is encoded columnar as {\"__cols\":[field names],\"__rows\":[[values]]}, so each field name is sent once instead of once per row. Fully lossless (no field or value is dropped or changed) and typically 40 to 52 percent fewer tokens on large results. Prefer true whenever token or inference cost matters. Default false returns standard indented JSON."New value: +"Set true for the same data in a compact shape: arrays of same-shaped objects arrive columnar as {\"__cols\":[names],\"__rows\":[[values]]}. Lossless, typically 40 to 52 percent fewer tokens."

Changed1 schema field changedJul 22, 2026

changedInput schema / properties / compact / description

Previous value: -"Return the same data in a token-optimized compact shape (minified, with same-shaped arrays encoded columnar) to reduce LLM token cost. Lossless: no fields are dropped. Default false."New value: +"Set true to receive the exact same data in a token-optimized shape that is cheaper for you to read: whitespace is stripped and every array of same-shaped objects is encoded columnar as {\"__cols\":[field names],\"__rows\":[[values]]}, so each field name is sent once instead of once per row. Fully lossless (no field or value is dropped or changed) and typically 40 to 52 percent fewer tokens on large results. Prefer true whenever token or inference cost matters. Default false returns standard indented JSON."

Changed1 schema field changedJul 22, 2026

addedInput schema / properties / compact

Added value: +{
+  "default": false,
+  "description": "Return the same data in a token-optimized compact shape (minified, with same-shaped arrays encoded columnar) to reduce LLM token cost. Lossless: no fields are dropped. Default false.",
+  "type": "boolean"
+}

First observedJul 8, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already declare readOnly/non-destructive, but the description adds genuine behavior beyond them: the result is deterministic per date, identical for all users unless a seed is supplied. That shared-vs-personalized semantic is the main thing an agent could get wrong, and it is disclosed.

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

Conciseness3/5

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

The first two sentences are tight and front-loaded, but the final sentence ('Perfect for daily guidance features, push notifications, wellness app widgets...') is marketing filler that does not help an agent invoke the tool and dilutes an otherwise efficient definition.

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

Completeness4/5

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

An output schema, annotations, and full parameter docs are present, so the description only needs to cover intent and the determinism/seed model, which it does. Nothing an agent needs to call it correctly is missing, though a note on what the teaser payload omits versus the detail endpoint would be a nice finishing touch.

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 coverage is 100% and each parameter has a detailed description, so the schema already carries the load. The description reinforces date/seed determinism at a conceptual level but adds no format, default, or constraint detail beyond what the schema states.

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?

States a specific verb and resource ('Get the crystal of the day') plus the key scope: deterministic crystal derived from the date. It explicitly distinguishes itself from the detail endpoint (get_crystals_id) and from the broader get_crystals family, so an agent can pick correctly without reading schemas.

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?

Gives a positive usage context (daily guidance, widgets, notifications) and routes the agent to /crystals/{id} when full healing properties are needed. It lacks an explicit 'do not use this when...' clause, but the alternative is named with its selection condition.

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

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