Crystals MCP Server by RoxyAPI

List crystal colors - Crystal color filter API

get_crystals_colors

Read-only

List all unique crystal colors available in the database. Use these values with the color filter on GET /crystals to find crystals by color. Essential reference endpoint for building color-based browsing of healing stones, visual crystal pickers, and filtering UI. The values are filter identifiers and stay in English under every lang, so a translated picker still submits a color the filter accepts.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`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
`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

TableJSON Schema

Name	Required	Description	Default
`count`	Yes
`colors`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 20, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "colors": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "count": {
+      "type": "number"
+    }
+  },
+  "required": [
+    "count",
+    "colors"
+  ],
+  "type": "object"
+}

Changed1 schema field changedSep 4, 2026

addedInput schema / properties / lang

Added value: +{
+  "default": "en",
+  "description": "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.",
+  "enum": [
+    "en",
+    "tr",
+    "de",
+    "es",
+    "hi",
+    "pt",
+    "fr",
+    "ru",
+    "zh-Hans",
+    "zh-Hant"
+  ],
+  "example": "en",
+  "type": "string"
+}

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

A4.4/5.0

Behavior4/5

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

Annotations already indicate a read-only, non-destructive operation. The description adds useful behavior beyond that: the values are filter identifiers and stay in English under every language, ensuring translated pickers still submit values the filter accepts.

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

Conciseness4/5

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

The description is short and front-loaded with the core behavior. The 'Essential reference endpoint' sentence adds use-case context but is slightly promotional compared to the rest.

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 zero-required-parameter read-only reference endpoint with an output schema and annotations, the description is complete. It explains what is returned, how to consume it downstream, and the key localization behavior.

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

Parameters4/5

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

Input schema coverage is 100%, so the baseline is 3. The description adds extra meaning for the lang parameter by explaining that color values are language-independent, while the compact parameter is adequately documented by the schema itself.

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 states the exact resource and operation: listing all unique crystal colors in the database. It also positions the tool as a filter reference, which makes it clearly distinct from sibling crystal endpoints.

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?

It explicitly says to use these values with the color filter on GET /crystals and gives concrete use cases like color-based browsing and filter UIs. It does not mention exclusions or alternatives, but the context is clear enough.

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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