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Colour Memory

by app.railway.up.colour-memory-api-production
OverviewDiscussionsAdmin

Compare Two Colours — Perceptual and Cultural

colour_compare
Read-only

Deep perceptual and semantic comparison between any two hex values. Returns quantified differences in LRV, chroma, hue angle, warmth, and CIEDE2000 distance, plus cultural context on both — which is more authoritative, more saturated, more stable under different illuminants, and what each has historically signified. Use when choosing between two colours or explaining why one works better than another. Not a harmony tool — this is a decision and reasoning tool.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
hex_aYesFirst colour hex e.g. '#003366'
hex_bYesSecond colour hex e.g. '#1877F2'

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "description": "Structured JSON response. Shape varies by tool; most return an 'ok' boolean plus a 'result' or 'results' field with the tool's data payload.",
+  "type": "object"
+}
  2. Changed1 schema field changed
    • changedOutput schema / (root)
      Previous value: -{
-  "properties": {
-    "error": {
-      "type": "string"
-    },
-    "ok": {
-      "type": "boolean"
-    },
-    "result": {
-      "type": [
-        "object",
-        "array",
-        "string",
-        "null"
-      ]
-    }
-  },
-  "type": "object"
-}New value: +null
  3. Added

TDQS

A4.5/5.0
Behavior4/5

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

The annotation readOnlyHint=true already discloses non-destructive behavior. The description adds meaningful behavioral context by enumerating the return content — LRV, chroma, hue angle, warmth, CIEDE2000 distance, and cultural context — and notes the tool's decision-support function, going beyond what annotations provide.

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?

Three sentences, front-loaded with the core action, followed by output details and usage guidance. Every sentence contributes distinct information: what it does, what it returns, and when to use it. No filler or repetition.

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?

With a simple 2-parameter interface and an output schema present, the description is fully sufficient. It explains the tool's purpose, output categories, usage contexts, and explicitly rejects the harmony-tool role. An agent can confidently select and invoke this tool without ambiguity.

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%, with both hex_a and hex_b described and example formats provided. The description phrases them as 'any two hex values,' reinforcing the relationship between parameters, but does not need to add further detail since the schema already carries the semantic load.

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 opens with a specific verb and resource: 'Deep perceptual and semantic comparison between any two hex values.' It lists concrete output dimensions and clearly distinguishes itself from harmony tools with 'Not a harmony tool — this is a decision and reasoning tool,' setting it apart from siblings like colour_harmonies.

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

Usage Guidelines5/5

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

Provides explicit guidance: 'Use when choosing between two colours or explaining why one works better than another.' It also states an exclusion ('Not a harmony tool'), which helps an agent decide against this tool when harmony-related tasks arise.

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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