Colour Memory

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

Match to Commercial Paint System

colour_match_paint

Read-only

Find the nearest named colour in commercial paint systems including Farrow and Ball and Little Greene.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "hex_val": "<hex_val>"
    },
    "name": "colour_match_paint"
  }
}

Input Schema

Name	Required	Description
`n`	No	Number of matches (default 3)
`brand`	No	Optional brand filter: 'farrow' or 'little_greene'
`hex_val`	Yes	Hex value e.g. '#003153'

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedJun 20, 2026

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"
+}

Changed1 schema field changedJun 17, 2026

changedOutput schema / (root)

Previous value: -{
-  "properties": {
-    "error": {
-      "type": "string"
-    },
-    "ok": {
-      "type": "boolean"
-    },
-    "result": {
-      "type": [
-        "object",
-        "array",
-        "string",
-        "null"
-      ]
-    }
-  },
-  "type": "object"
-}New value: +null

AddedJun 7, 2026

TDQS

A4.2/5.0

Behavior4/5

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

The readOnlyHint annotation already declares this as a safe operation. The description adds value by specifying the brand scope ('Farrow and Ball and Little Greene'), which is not in the annotation. However, it does not clarify whether the tool supports additional brands beyond these two, and the 'including' wording could be ambiguous. The behaviour of matching a hex to a named colour is clear.

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?

The description is a single sentence that is front-loaded with the verb and resource, containing no filler. It efficiently conveys the essential purpose.

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?

The tool has low complexity, a complete input schema, an output schema, and a readOnlyHint annotation. The description covers the core purpose and specific brands. It is slightly ambiguous about whether other paint brands are supported, but the overall context is sufficient for an agent to understand what the tool does and what it returns.

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 100%, with each parameter already having clear descriptions (n: 'Number of matches', brand: 'Optional brand filter', hex_val: 'Hex value'). The description does not need to add parameter details. It does not go beyond the schema, but that is acceptable given the high coverage.

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 clearly states the tool's function: 'Find the nearest named colour in commercial paint systems including Farrow and Ball and Little Greene.' This uses a specific verb ('find') and resource ('nearest named colour in commercial paint systems'), and explicitly names the included brands, which distinguishes it from sibling tools like colour_namer or colour_compare that may handle generic colour naming or comparison.

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 implies usage for matching a hex value to a commercial paint system colour, which is clear context. It does not explicitly list alternatives or when-not-to-use, but the mention of 'commercial paint systems' and specific brands provides sufficient guidance for selection among the many sibling palette/colour tools.

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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