Vizcom MCP

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vizcom_make_region_mask

Create a PNG region mask from normalized rectangle coordinates on a source PNG, using white for selected areas and black for protected areas. No image generation involved.

Instructions

Create a PNG selection mask matching a source PNG. Rectangle coordinates are normalized 0–1, white selected / black protected. No generation.

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": {
      "file": "<file>",
      "rectangles": "<rectangles>"
    },
    "name": "vizcom_make_region_mask"
  }
}

Input Schema

Name	Required	Description	Default
`file`	Yes
`rectangles`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 6, 2026

TDQS

A3.7/5.0

Behavior4/5

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

Annotations already declare non-read-only, non-destructive, non-idempotent, and open-world, so the description does not need to restate safety. It adds real behavioral context beyond them: the output is a PNG mask matching the source, with white=selected and black=protected, and no generation is performed. It does not say where the mask is stored or how it is referenced afterward.

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 short sentences with zero filler, front-loaded with the core action and followed by the two facts an agent cannot infer: the coordinate convention and the mask color semantics.

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?

For a two-parameter, no-output-schema tool the mask color convention and normalization are well covered, but `file` is left entirely undefined and the return value (a path, an ID, an inline image?) is unaddressed even though no output schema exists to fill the gap.

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 0%, so the description carries the burden. It usefully explains that rectangle coordinates are normalized 0–1 and that multiple rectangles combine into the selection, but it says nothing about the `file` parameter (path, ID, or URL) or the 20-rectangle cap. Partial compensation only.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and artifact: 'Create a PNG selection mask matching a source PNG,' and the closing 'No generation' separates it from the render/generate siblings. It does not name vizcom_edit_region, which is the closest ambiguous neighbor, but the mask-vs-render distinction is clear.

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?

Usage is only implied: the phrase 'No generation' signals this is a cheap local mask step rather than a render, but it never states when to call this instead of vizcom_edit_region or whether a render must follow. No prerequisites or exclusions are given.

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