pebble-mcp

by dbonomo

Overview Schema Source Related Servers Discussions Admin

Python

Local

color_nearest

Map any color to the nearest Pebble GColor, and check contrast and legibility against an optional background.

Instructions

Nearest of the 64 Pebble GColors to an arbitrary color.

Args: color: a hex string ("#RRGGBB" / "RRGGBB" / shorthand) or an "r,g,b" triple. background: optional background color; when given, the contrast ratio and legibility of the matched color on it are also reported.

Returns the matched GColor name, hex, C constant, packed ARGB8 byte, sunlight-corrected display hex, and sRGB distance to the input.

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": {
      "color": "<color>"
    },
    "name": "color_nearest"
  }
}

Input Schema

Name	Required	Description	Default
`color`	Yes
`background`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 2, 2026

TDQS

A4.4/5.0

Behavior4/5

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

With no annotations, the description reveals key behavioral aspects: it returns multiple representations (name, hex, C constant, packed byte, sunlight-corrected hex, sRGB distance) and optionally reports contrast ratio. It does not discuss error handling, but for a pure lookup tool this is a minor omission.

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 compact and well-organized: a one-line purpose, an Args explanation, and a Returns list. Every sentence adds useful information without redundancy.

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 simple two-parameter read-only tool with an output schema, the description fully covers input formats, optional behavior, and output values. No significant gaps remain.

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

Parameters5/5

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

Schema has zero descriptions, so the description fully compensates by detailing the accepted color formats (hex with/or without hash, shorthand, or r,g,b triple) and explaining the background parameter for contrast/legibility reporting. This is richer than the bare schema.

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 opening sentence clearly states the tool maps an arbitrary color to the nearest of 64 Pebble GColors. It uses a specific verb/resource combination and distinguishes itself from sibling tools by its focused palette conversion purpose.

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

Usage Guidelines3/5

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

The description implies usage for when you need to find a Pebble GColor nearest to an arbitrary color, but it does not explicitly mention when not to use it or offer alternatives among sibling tools. Lacks explicit exclusions.

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