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pixel_convert

Convert values between CSS units px, pt, rem, em, and percent. Specify source and target units, with an optional base font size for accurate conversions.

Instructions

Convert between px, pt, rem, em, and percent CSS units.

Parameters:
    value — Value to convert.
    from_unit — Source unit: 'px', 'pt', 'rem', 'em', 'percent'.
    to_unit — Target unit.
    base_size — Base font size (default: 16px).

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": {
      "value": "<value>",
      "from_unit": "<from_unit>",
      "to_unit": "<to_unit>"
    },
    "name": "pixel_convert"
  }
}

Input Schema

Name	Required	Description	Default
`value`	Yes
`from_unit`	Yes
`to_unit`	Yes
`base_size`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.4.1Jun 22, 2026

TDQS

B3.4/5.0

Behavior2/5

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

With no annotations, the description bears full responsibility for behavioral disclosure. It only lists parameters without explaining behavior for invalid inputs, error handling, or how base_size affects conversion. This is insufficient for safe tool invocation.

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 concise and uses a structured list for parameters. It is front-loaded with the purpose statement. Every sentence adds value, though the parameter explanations are terse yet sufficient.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the output schema exists, return values need not be explained. However, for a tool with many sibling converters, more context on limitations (e.g., percent conversion requires base_size) would improve completeness. The description is adequate but not thorough.

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?

Schema description coverage is 0%, so the description compensates by adding meaning to each parameter: 'value', 'from_unit', 'to_unit', and 'base_size' with a default. It clarifies accepted units and default behavior, which the schema lacks.

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 converts between specific CSS units (px, pt, rem, em, percent) with a verb and resource. It distinguishes itself from sibling conversion tools by targeting CSS units, leaving no ambiguity.

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

Usage Guidelines2/5

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

The description provides no guidance on when to use this tool versus alternatives like 'convert_units' or other unit converters it only states what it does, not when to prefer it or when not to use it.

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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