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The validate command analyzes Minecraft projects for errors, warnings, and adherence to best practices. It supports multiple validation suites and can process single projects or batch validate multiple projects.

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Syntax

mct validate [suite] [exclusions] [aggregateReports] [options]

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Arguments

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suite
string
default:"main"
The validation suite to run.Choices:
  • all - Run all available validation tests
  • default - Default validation suite
  • addon - Strict validation for marketplace add-ons
  • currentplatform - Validate against current platform versions
  • main - Most commonly used validation tests (default)
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exclusions
string
Comma-separated list of test codes to exclude from validation.Example: PATHLENGTH,PACKSIZE
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aggregateReports
string
Control report aggregation across multiple projects.Choices:
  • aggregate - Aggregate reports and build content index
  • aggregatenoindex - Aggregate reports without building index
  • true, 1 - Same as aggregate
  • false, 0 - No aggregation

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Options

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-i, --input-folder
string
Path to the project folder to validate.
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-if, --input-file
string
Path to a packaged file (MCWorld, MCTemplate, MCPack, MCAddon) to validate.
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-o, --output-folder
string
default:"out"
Path where validation reports will be written.
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-show, --display-only
boolean
Display validation results in the console instead of writing report files.
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--threads
number
default:"8"
Number of worker threads for parallel validation. Use 1 for sequential processing.
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-lv, --log-verbose
boolean
Show detailed logging information during validation.
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-psw, --project-starts-with
string
Only validate projects whose names start with this prefix. Useful for batch processing subsets.
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-ot, --output-type
string
Type of output to generate.Choices:
  • noreports - Skip report file generation

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Examples

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Validate a single project folder

mct validate -i ./my-addon -show

Project name: My Addon
Project description: An example Minecraft addon

✓ No errors found
⚠ 2 warnings
  - [BP001] Script file missing proper header comment
  - [RP003] Texture resolution exceeds recommended size

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Validate with strict addon suite

mct validate addon -i ./my-addon -show --log-verbose
This runs the strict marketplace validation suite with detailed logging.

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Validate a packaged file

mct validate -if ./packages/myaddon.mcaddon -show

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Batch validate multiple projects

mct validate -i ./projects -o ./validation-results aggregate
This validates all projects in the ./projects folder and creates aggregated reports.

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Validate with exclusions

mct validate main "PATHLENGTH,PACKSIZE" -i ./my-addon -show
Validates the project but skips path length and pack size checks.

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Validate with parallel processing

mct validate -i ./projects --threads 16 aggregate
Uses 16 worker threads to validate projects in parallel.

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Sequential validation (debugging)

mct validate -i ./my-addon --threads 1 -show -lv
Uses single-threaded processing with verbose logging for debugging.

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Validation Output

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Console Output

When using -show, validation results appear in the console: 
┌─────┐
│ ▄ ▄ │ Minecraft Creator Tools (preview) command line
│ ┏▀┓ │ See https://aka.ms/mcthomepage for more info.
└─────┘

=== Validation Results ===

Errors: 0
Warnings: 2
Info: 5

⚠ Warning [BP001]: Missing header comment in scripts/main.js:1
⚠ Warning [RP003]: Large texture file at textures/entity/player.png (4096x4096)

ℹ Info: Found 3 entities
ℹ Info: Found 5 items
ℹ Info: Found 2 blocks

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File Output

Without -show, reports are written to the output folder: 
out/
├── my-addon.json          # Detailed validation report
├── my-addon.csv           # CSV format for spreadsheet analysis
└── all.csv                # Aggregated report (if using aggregate)

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Validation Suites

The most commonly used validation suite. Checks for:
  • Syntax errors in JSON files
  • Missing required files
  • Invalid references
  • Common mistakes
  • Basic best practices

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Multi-Project Validation

The CLI supports three project detection modes:

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Single Project

Point to a folder containing a Minecraft project: 
mct validate -i ./my-addon

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Multi-Level Multi-Project

Parent folder with subfolders containing zip files: 
projects/
├── coolgame/
│   ├── coolgame.mcaddon
│   └── coolgame.data.json
└── swellgame/
    ├── swellgame.mcaddon
    └── swellgame.data.json

mct validate -i ./projects aggregate

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Children-of-Folder Multi-Project

Folder with multiple project subfolders or zip files: 
projects/
├── addon1/
│   ├── behavior_packs/
│   └── resource_packs/
├── addon2/
│   ├── behavior_packs/
│   └── resource_packs/
└── addon3.mcaddon

mct validate -i ./projects aggregate

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Performance Optimization

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Thread Configuration

The --threads option controls parallelization:
  • Default (8 threads): Good balance for most systems
  • More threads (16+): Better for validating many small projects
  • Sequential (1 thread): Better for debugging or memory-constrained environments
# Maximum parallelization
mct validate -i ./projects --threads 16

# Sequential for debugging
mct validate -i ./my-addon --threads 1 -lv

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Memory Considerations

Each worker thread has a 16GB memory limit. For large projects, consider:
  • Using fewer threads
  • Validating projects individually
  • Using output files instead of -show

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Aggregated Reports

When validating multiple projects with the aggregate option: Generated Files:
  • all.csv - All validation issues across projects
  • allprojects.csv - Summary statistics per project
  • mci/index.json - Content index of all projects
Example: 
mct validate -i ./marketplace-addons -o ./reports aggregate

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Exit Codes

CodeDescription
0Validation passed with no errors
53Internal processing error
56Test failure
57Validation error found

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Troubleshooting

Reduce the number of threads or use sequential processing:
mct validate -i ./large-project --threads 1
Use fewer threads and output to files instead of console:
mct validate -i ./projects --threads 4 -o ./results
Use the -psw option to filter or validate individually:
# Only projects starting with "test"
mct validate -i ./projects -psw test

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