jasonjgardner/blockbench-mcp-overview

Blockbench MCP Overview

Complete guide to the Blockbench MCP server for AI-assisted 3D modeling.

What is Blockbench MCP?

An MCP server that exposes Blockbench functionality to AI agents through:

• Tools: Actions that create, modify, or query the 3D model
• Resources: Read-only data endpoints for model information
• Prompts: Reusable guidance for specific workflows

Tool Categories

| Domain | Tools | Purpose | |--------|-------|---------| | Animation | 7 | Keyframes, rigs, curves, timeline | | Camera | 3 | Screenshots, camera control | | Cubes | 2 | Cube creation and modification | | Elements | 8 | Groups, outliner, duplication, selection/filtering | | Export | 2 | Compile and save models via codecs | | History | 4 | Undo, redo, checkpoint, inspect stack | | Import | 1 | GeoJSON import | | Mesh | 11 | Spheres, cylinders, extrusion, vertices | | Paint | 12 | Brushes, fill, shapes, layers | | Texture | 13 | Textures, PBR materials | | UI | 4 | Actions, evaluation, dialogs | | UV | 3 | UV mapping | | Hytale | 12 | Hytale-specific (requires plugin) |

Resources

| Resource | URI Pattern | Data | |----------|-------------|------| | projects | projects://{id} | Project info, formats | | textures | textures://{id} | Texture metadata | | nodes | nodes://{id} | 3D node data | | hytale-format | hytale://format | Hytale format info | | hytale-attachments | hytale://attachments/{id} | Attachment collections | | hytale-pieces | hytale://pieces/{id} | Attachment pieces | | hytale-cubes | hytale://cubes/{id} | Hytale cube properties |

Prompts

| Prompt | Purpose | |--------|---------| | blockbench_native_apis | Blockbench v5.0 API security guide | | blockbench_code_eval_safety | Safe code evaluation patterns | | model_creation_strategy | Model creation guidance | | hytale_model_creation | Hytale modeling guide | | hytale_animation_workflow | Hytale animation guide | | hytale_attachments | Hytale attachments guide |

Quick Start Workflows

Create a Simple Model

# 1. Create project
create_project: name="my_model", format="bedrock"

# 2. Create texture
create_texture: name="skin", width=64, height=64

# 3. Add bone structure
add_group: name="root", origin=[0, 0, 0]
add_group: name="body", parent="root", origin=[0, 12, 0]

# 4. Add geometry
place_cube: elements=[{name: "torso", from: [-4, 12, -2], to: [4, 24, 2]}], group="body"

# 5. Apply texture
apply_texture: id="torso", texture="skin"

# 6. View result
capture_screenshot

Create and Animate

# 1. Build model (see above)

# 2. Create animation
create_animation: name="idle", animation_length=2.0, loop=true

# 3. Add keyframes
manage_keyframes: bone_name="body", channel="rotation",
  keyframes=[
    {time: 0, values: [0, 0, 0]},
    {time: 1.0, values: [0, 5, 0]},
    {time: 2.0, values: [0, 0, 0]}
  ]

# 4. Play animation
animation_timeline: action="play"

Paint a Texture

# 1. Create texture
create_texture: name="block", width=16, height=16, fill_color="#8B4513"

# 2. Add details
draw_shape_tool: shape="rectangle", start={x: 2, y: 2}, end={x: 14, y: 14}, color="#A0522D"
paint_with_brush: coordinates=[{x: 8, y: 8}], brush_settings={color: "#654321", size: 2}

# 3. View texture
get_texture: texture="block"

Tool Patterns

Information Gathering

list_outline                   # View model hierarchy
list_textures                  # View textures
list_materials                 # View PBR materials
list_export_formats            # View available export codecs
get_undo_stack                 # Inspect undo history
find_elements_by_criteria      # Search model by name, type, size, parent
filter_by_material             # Find elements referencing a texture
hytale_get_format_info         # View Hytale format (if active)

Modification Pattern

Most modification tools follow:

1. Identify target by ID or name
2. Specify changes
3. Changes are recorded for undo

Screenshot Workflow

set_camera_angle: position=[0, 20, 50], rotation=[0, 0, 0], projection="perspective"
capture_screenshot      # 3D view only
capture_app_screenshot  # Entire Blockbench window

Evaluation (Advanced)

risky_eval: code="Cube.all.length"  # Query Blockbench directly
trigger_action: action="undo"       # Trigger Blockbench actions

Undo & Checkpoints

Use history tools to branch, recover, and mark progress in multi-step agent workflows. Prefer undo/redo over trigger_action: action="undo".

# Mark a state before risky work
save_checkpoint: name="before_arm_rework"

# Make changes...
modify_cube: id="arm_left", rotation=[0, 45, 0]
duplicate_element: id="arm_left", newName="arm_right", offset=[-8, 0, 0]

# Didn't like the result - roll back 2 steps
undo: steps=2

# Inspect what's in the stack
get_undo_stack: limit=10
# → { index, total, can_undo, can_redo, entries: [...] }

The checkpoint appears in get_undo_stack as [checkpoint] before_arm_rework, so an agent can count entries between the current index and the checkpoint to know how many times to call undo.

Export

Export the current project through any registered Blockbench codec. Content is returned in the response; optionally written to disk.

# Discover codecs (filter to current format's compatible codecs)
list_export_formats: only_current_format=true

# Compile and return content (default path: none, content returned)
export_model: codec_id="obj"

# Compile, write to disk (requires Blockbench v5.0+ fs permission prompt)
export_model: codec_id="gltf", path="C:/models/character.gltf"

# Large files: skip content in response, only write
export_model: codec_id="project", path="C:/models/save.bbmodel", max_content_length=0

Content is truncated at max_content_length characters (default 100,000) to protect the MCP context window. Use byte_length in the response to see the real size.

Domain Integration

Model + Texture

# Create model
place_cube: elements=[{name: "block", from: [0,0,0], to: [16,16,16]}]

# Create texture
create_texture: name="block_tex", width=16, height=16

# Paint texture
paint_fill_tool: texture_id="block_tex", x=0, y=0, color="#00FF00", fill_mode="element"

# Apply
apply_texture: id="block", texture="block_tex"

Model + Animation

# Create bone hierarchy (important for animation)
add_group: name="root", origin=[0, 0, 0]
add_group: name="arm", parent="root", origin=[4, 12, 0]

# Add geometry to bones
place_cube: elements=[{name: "arm_geo", from: [0, 0, -1], to: [2, 10, 1]}], group="arm"

# Animate the bone
create_animation: name="wave", animation_length=1.0
manage_keyframes: bone_name="arm", channel="rotation",
  keyframes=[{time: 0, values: [0, 0, 0]}, {time: 0.5, values: [0, 0, 90]}]

PBR Material Workflow

# Create textures for each channel
create_texture: name="stone_color", width=16, height=16
create_texture: name="stone_normal", width=16, height=16, fill_color="#8080FF"
create_texture: name="stone_mer", width=16, height=16, fill_color=[0, 0, 200, 255]

# Create material
create_pbr_material: name="stone", textures={
  color: "stone_color",
  normal: "stone_normal",
  mer: "stone_mer"
}

# Configure
configure_material: material_id="stone", config={
  metalness_emissive_roughness: {metalness: 0, emissive: 0, roughness: 0.9}
}

Error Handling

Tools throw descriptive errors with suggestions:

• Element not found: "Use list_outline tool to see available elements"
• Texture not found: "Use list_textures tool to see available textures"
• Invalid format: "Current project is not using a Hytale format"

Best Practices

1. Query first: Use list_* tools to understand current state
2. Build hierarchy: Create bone structure before geometry
3. Set origins: Place group origins at pivot points for animation
4. Name elements: Use descriptive names for easy reference
5. Validate: Use hytale_validate_model for Hytale projects
6. Screenshot: Capture progress with capture_screenshot
7. Checkpoint before risk: Call save_checkpoint before experimental edits so undo can return cleanly
8. Filter before iterate: Prefer find_elements_by_criteria or filter_by_material over loading the full outline and filtering client-side

Tool Status

• stable: Production-ready
• experimental: Working but may change

Most tools are experimental but functional. Check tool annotations for current status.