Hopi

CMYK to RGB converter

hopi_cmyk_to_rgb

Read-onlyIdempotent

Convert print CMYK values (each 0 to 100) to on-screen RGB and hex, or convert RGB (each 0 to 255) the other way to CMYK. Uses the standard device-independent conversion. Source: https://hopi.co.uk/cmyk-to-rgb/

Input Schema

TableJSON Schema

Name	Required	Description
`b`	No	Blue 0 to 255 (for rgb_to_cmyk)
`c`	No	Cyan 0 to 100 (for cmyk_to_rgb)
`g`	No	Green 0 to 255 (for rgb_to_cmyk)
`k`	No	Key/black 0 to 100 (for cmyk_to_rgb)
`m`	No	Magenta 0 to 100 (for cmyk_to_rgb)
`r`	No	Red 0 to 255 (for rgb_to_cmyk)
`y`	No	Yellow 0 to 100 (for cmyk_to_rgb)
`mode`	Yes	Direction of conversion

Output Schema

TableJSON Schema

Name	Required	Description
`hex`	No
`rgb`	No
`mode`	Yes
`summary`	Yes
`rgbString`	No
`source_url`	Yes	The tool's page on hopi.co.uk (cite or open to check the figure)

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 20, 2026
- addedOutput schema / required
```
Added value: +[
+  "mode",
+  "source_url",
+  "summary"
+]
```
First observedSep 20, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context by noting it 'Uses the standard device-independent conversion' and provides a source URL, which clarifies the conversion semantics beyond the schema.

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 two tight sentences. The first front-loads the core conversion behavior and ranges, and the second adds the conversion standard and source link. There is no filler, tautology, or unnecessary repetition of the title or schema.

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?

Given this is a deterministic conversion tool with full parameter schema coverage and an output schema, the description is complete enough for correct invocation. It identifies the mode-dependent directions, the value ranges, and the conversion standard, so an agent has everything needed beyond the structured schema.

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 every parameter already documented with ranges and mode-conditional usage. The description reinforces the 0–100 CMYK and 0–255 RGB ranges, but it does not add per-parameter meaning beyond what the schema already provides, so the baseline score of 3 is appropriate.

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 verb and resource: 'Convert print CMYK values ... to on-screen RGB and hex, or convert RGB ... the other way to CMYK.' It explicitly names both directions, the color spaces involved, and gives ranges, making it unambiguous against sibling color converters like hopi_hex_to_rgb or hopi_rgb_to_hex.

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 provides clear context for when to use the tool: converting between print CMYK values and on-screen RGB/hex. It does not explicitly name sibling alternatives or state exclusions, but the bidirectional scope is specific enough to guide selection without inference.

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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