# BlenderMCP Architecture & BDD Review - Features 16-27 (Add-on Tools)
**Review Date:** 2025-11-11
**Reviewer:** Architecture Guardian
**Scope:** Features 16-27 (Third-party add-on integrations for retopology)
---
## 1. Executive Summary
**CRITICAL FINDING:** Features 16-27 represent a significant implementation effort creating MCP tool wrappers for third-party Blender add-ons, but **NONE of these tools are functional** due to missing backend handlers in addon.py.
**Severity: BLOCKING - LLM Cannot Use These Tools**
### Key Issues:
- 12 new MCP tools registered in server.py (lines 310-338, 1283-1559)
- Well-structured tool implementations with proper validation and docstrings
- **ZERO backend handlers implemented in addon.py**
- Complete disconnect between MCP layer and Blender execution layer
- Tools will fail immediately when invoked by an LLM
### Impact:
- **0% functional** - All 12 tools return "Unknown command type" errors
- LLM cannot perform any manual retopology workflows
- Features 16-27 are completely non-functional despite code being present
- Significant wasted development effort without integration testing
---
## 2. Repository Snapshot
### Features 16-27 BDD Specifications
```
features/16_draw_xray.feature - Draw X-ray overlay for retopo visibility
features/17_retopoflow_start.feature - Initialize RetopoFlow sessions
features/18_quad_remesher.feature - Automatic quad-based remeshing
features/19_retopoflow_contours.feature - Draw cylindrical loops
features/20_retopoflow_polystrips.feature - Sketch feature-line strips
features/21_retopoflow_strokes.feature - Fill gaps with quad patches
features/22_retopoflow_brushes.feature - Relax and Tweak brushes
features/23_looptools_relax.feature - Smooth topology operations
features/24_looptools_space.feature - Equalize loop spacing
features/25_looptools_bridge_flatten.feature - Bridge and flatten operations
features/26_machin3_surface_slide.feature - Surface-constrained sliding
features/27_quadwrap.feature - Cylindrical sleeve wrapping
```
### Implementation Files Created
```
src/retopo_tools/draw_xray.py - 76 lines (Draw X-ray implementation)
src/tools/integrations/retopoflow.py - 269 lines (5 RetopoFlow tools)
src/tools/integrations/quad_remesher.py - 77 lines (Quad Remesher tool)
src/tools/integrations/looptools.py - 206 lines (4 LoopTools tools)
src/tools/integrations/machin3.py - 63 lines (Surface Slide tool)
src/tools/integrations/quadwrap.py - 70 lines (QuadWrap tool)
```
### Server Registration
- `src/server.py` lines 313-338: Tool imports added
- `src/server.py` lines 1283-1559: 12 MCP tool wrappers registered with `@mcp.tool()` decorators
### Missing Integration
- `addon.py` lines 204-253: Handler dictionary **DOES NOT** include any of the 12 new tools
- `addon.py`: **NO** handler methods implemented for features 16-27
---
## 3. Architecture & Structure Compliance
### 3.1 Server vs Modules ✓ COMPLIANT
**Finding:** The new tool implementations follow architectural patterns correctly.
- server.py contains only thin wrappers (lines 1283-1559)
- All business logic properly isolated in dedicated modules
- No domain logic leaked into server.py
- Proper separation maintained between MCP layer and implementation
**Example (lines 1310-1323):**
```python
@mcp.tool()
def retopoflow_start(ctx: Context, mode: str = "AT_ACTIVE") -> str:
"""Initialize RetopoFlow session aligned to source mesh..."""
return retopoflow_start_impl(ctx, get_blender_connection(), mode)
```
### 3.2 Modules & Dependencies ✓ COMPLIANT
**Organization:**
- Draw X-ray placed in `retopo_tools/` (specialized retopo tool) ✓
- Integration tools placed in `tools/integrations/` (external add-ons) ✓
- No circular dependencies detected ✓
- Clean module boundaries maintained ✓
**Dependency Flow:**
```
server.py → tools/integrations/*.py → (should be) → addon.py handlers
^^^^^^^^^^^^
MISSING LINK!
```
### 3.3 Signatures & Docstrings ✓ EXCELLENT
**Quality Assessment:** All 12 tools have comprehensive documentation.
**Example - retopoflow.py line 22-38:**
```python
def retopoflow_start(
ctx: Context,
blender_connection,
mode: str = "AT_ACTIVE"
) -> str:
"""
Initialize RetopoFlow session aligned to source mesh.
Starts RetopoFlow with snapping, overlay, and merge settings
configured for retopology. Creates a new retopo object and
activates RetopoFlow mode in Edit Mode.
Parameters:
- mode: Initialization mode - 'AT_ACTIVE', 'AT_CURSOR' (default: 'AT_ACTIVE')
Returns status message with RetopoFlow initialization details.
"""
```
**Strengths:**
- Clear parameter descriptions with types and defaults
- Explains what the tool does and why you'd use it
- Returns clause describes output format
- Suitable for LLM consumption
### 3.4 Error Handling & Logging ✓ GOOD
**Pattern Observed:** Consistent error handling in all tools.
**Example - quad_remesher.py lines 44-58:**
```python
if target_quads < 100 or target_quads > 1000000:
return f"Error: Invalid target_quads '{target_quads}'. Must be between 100 and 1000000."
if adaptive_size < 0.0 or adaptive_size > 1.0:
return f"Error: Invalid adaptive_size '{adaptive_size}'. Must be between 0.0 and 1.0."
result = blender_connection.send_command("quad_remesher_remesh", {
"target_quads": target_quads,
"adaptive_size": adaptive_size,
"adaptive_quad_count": adaptive_quad_count,
"guides": guides
})
if "error" in result:
return f"Error: {result['error']}"
```
**Strengths:**
- Pre-validates inputs with clear ranges
- Uses try/except blocks consistently
- Logs errors via logger
- Returns user-friendly error messages
- Provides actionable feedback
### 3.5 Critical Architectural Violation ✗ BLOCKING
**Issue:** Complete disconnect between MCP tools and Blender handlers.
**addon.py lines 204-253** - Handler dictionary:
```python
handlers = {
"get_scene_info": self.get_scene_info,
"mesh_stats": self.mesh_stats,
"add_mirror_modifier": self.add_mirror_modifier,
# ... existing handlers ...
"export_asset": self.export_asset,
}
# Features 16-27 handlers MISSING:
# "draw_xray_enable": ???
# "retopoflow_start": ???
# "rf_contours_draw": ???
# "rf_polystrips_draw": ???
# "rf_strokes_fill": ???
# "rf_brush": ???
# "quad_remesher_remesh": ???
# "looptools_relax": ???
# "looptools_space": ???
# "looptools_bridge": ???
# "looptools_flatten": ???
# "surface_slide_toggle": ???
# "quadwrap_wrap": ???
```
**Line 294 in addon.py:**
```python
else:
return {"status": "error", "message": f"Unknown command type: {cmd_type}"}
```
**Result:** ALL 12 tools will hit this error path when invoked.
---
## 4. BDD Scenario Coverage & Validation
### 4.1 Tool-by-Tool BDD Compliance Status
| Feature | BDD File | Tool Name | MCP Registered | Implementation | Addon Handler | Status |
|---------|----------|-----------|----------------|----------------|---------------|---------|
| 16 | `16_draw_xray.feature` | `draw_xray_enable` | ✓ line 1283 | ✓ `retopo_tools/draw_xray.py` | ✗ MISSING | BLOCKED |
| 17 | `17_retopoflow_start.feature` | `retopoflow_start` | ✓ line 1310 | ✓ `tools/integrations/retopoflow.py:22` | ✗ MISSING | BLOCKED |
| 19 | `19_retopoflow_contours.feature` | `rf_contours_draw` | ✓ line 1324 | ✓ `tools/integrations/retopoflow.py:64` | ✗ MISSING | BLOCKED |
| 20 | `20_retopoflow_polystrips.feature` | `rf_polystrips_draw` | ✓ line 1344 | ✓ `tools/integrations/retopoflow.py:118` | ✗ MISSING | BLOCKED |
| 21 | `21_retopoflow_strokes.feature` | `rf_strokes_fill` | ✓ line 1366 | ✓ `tools/integrations/retopoflow.py:172` | ✗ MISSING | BLOCKED |
| 22 | `22_retopoflow_brushes.feature` | `rf_brush` | ✓ line 1384 | ✓ `tools/integrations/retopoflow.py:215` | ✗ MISSING | BLOCKED |
| 18 | `18_quad_remesher.feature` | `quad_remesher_remesh` | ✓ line 1409 | ✓ `tools/integrations/quad_remesher.py:18` | ✗ MISSING | BLOCKED |
| 23 | `23_looptools_relax.feature` | `looptools_relax` | ✓ line 1438 | ✓ `tools/integrations/looptools.py:21` | ✗ MISSING | BLOCKED |
| 24 | `24_looptools_space.feature` | `looptools_space` | ✓ line 1457 | ✓ `tools/integrations/looptools.py:65` | ✗ MISSING | BLOCKED |
| 25 | `25_looptools_bridge_flatten.feature` | `looptools_bridge` | ✓ line 1475 | ✓ `tools/integrations/looptools.py:113` | ✗ MISSING | BLOCKED |
| 25 | `25_looptools_bridge_flatten.feature` | `looptools_flatten` | ✓ line 1496 | ✓ `tools/integrations/looptools.py:163` | ✗ MISSING | BLOCKED |
| 26 | `26_machin3_surface_slide.feature` | `surface_slide_toggle` | ✓ line 1515 | ✓ `tools/integrations/machin3.py:18` | ✗ MISSING | BLOCKED |
| 27 | `27_quadwrap.feature` | `quadwrap_wrap` | ✓ line 1539 | ✓ `tools/integrations/quadwrap.py:18` | ✗ MISSING | BLOCKED |
**Summary:**
- **12/12 tools** have BDD specifications ✓
- **12/12 tools** registered in MCP server ✓
- **12/12 tools** have Python implementations ✓
- **0/12 tools** have addon.py handlers ✗
- **0/12 tools** are functional ✗
### 4.2 BDD Scenario Mapping
Each feature file follows proper Gherkin structure with:
- Background section defining preconditions
- Scenario outlines with parameter examples
- Clear Given/When/Then steps
- Expected outcomes defined
**Example - Feature 18 (Quad Remesher):**
```gherkin
Scenario Outline: Remesh with target count and adaptive controls
Given the high-poly source is selected
When I call quad_remesher_remesh with target_quads=<target_quads>
adaptive_size=<adaptive_size> adaptive_quad_count=<adaptive_quad_count>
guides="<guides>"
Then a new quad-only object is created with density near the target
And the original object is left unchanged and can be hidden for comparison
And density is distributed according to curvature and guides
And the result is suitable for subsequent manual refinement
Examples:
| target_quads | adaptive_size | adaptive_quad_count | guides |
| 10000 | 0.50 | true | "USE_HARD_EDGES;USE_AUTO_DETECT_ANGLES=45" |
```
**BDD Quality:** EXCELLENT - All scenarios are testable and specify expected behavior clearly.
---
## 5. LLM Usability Assessment
### 5.1 Tool Discoverability ✓ EXCELLENT
**MCP Discovery:** All 12 tools properly registered and discoverable.
An LLM invoking "list available tools" would see:
```
- draw_xray_enable
- retopoflow_start
- rf_contours_draw
- rf_polystrips_draw
- rf_strokes_fill
- rf_brush
- quad_remesher_remesh
- looptools_relax
- looptools_space
- looptools_bridge
- looptools_flatten
- surface_slide_toggle
- quadwrap_wrap
```
### 5.2 Documentation Quality ✓ EXCELLENT
**For LLM Understanding:**
- Tool names are descriptive and semantic ✓
- Docstrings explain purpose, parameters, and returns ✓
- Parameter types and defaults clearly specified ✓
- Usage context provided (when to use each tool) ✓
**Example - looptools_bridge (line 1475):**
```python
@mcp.tool()
def looptools_bridge(
ctx: Context,
segments: int = 2,
smooth: float = 0.0,
merge_endpoints: bool = False
) -> str:
"""
Connect gaps cleanly with quad rows.
Bridges two compatible boundary loops across a gap, filling it
with clean quad rows while preserving boundary alignment.
Parameters:
- segments: Number of segments between loops (default: 2)
- smooth: Smoothing factor 0-1 (default: 0.0)
- merge_endpoints: Merge endpoints of loops (default: False)
Returns status message with bridge operation details.
"""
```
An LLM can clearly understand:
- What the tool does (bridges gaps between loops)
- When to use it (connecting boundary loops)
- What parameters control (segments, smoothing, endpoint merging)
- What to expect back (status message with details)
### 5.3 Parameter Validation ✓ GOOD
All tools validate inputs before sending to Blender:
**Example - rf_contours_draw (lines 85-93):**
```python
valid_spacing = ['UNIFORM', 'TIGHT']
if spacing_hint not in valid_spacing:
return f"Error: Invalid spacing_hint '{spacing_hint}'. Must be one of {valid_spacing}."
if stroke_count < 1 or stroke_count > 100:
return f"Error: Invalid stroke_count '{stroke_count}'. Must be between 1 and 100."
if ring_segments < 3 or ring_segments > 128:
return f"Error: Invalid ring_segments '{ring_segments}'. Must be between 3 and 128."
```
**Benefit for LLM:** Clear error messages guide correction of invalid parameters.
### 5.4 Blocking Issues ✗ CRITICAL
**Issue 1: Execution Failure**
- **Severity:** CRITICAL
- **Impact:** 100% failure rate
- **Description:** When LLM invokes any of the 12 tools, it receives:
```json
{"status": "error", "message": "Unknown command type: rf_contours_draw"}
```
- **LLM Experience:** Tool appears available but always fails
- **User Impact:** Confusing error messages, broken workflows
**Issue 2: No Feedback Loop**
- **Severity:** HIGH
- **Impact:** LLM cannot learn correct usage
- **Description:** Error message doesn't explain the tool exists but lacks backend
- **LLM Experience:** May retry with different parameters, wasting tokens
- **User Impact:** Time wasted debugging what appears to be user error
**Issue 3: Incomplete Workflow**
- **Severity:** HIGH
- **Impact:** Manual retopology workflows completely blocked
- **Description:** Features 16-27 were designed as integrated workflow
- **LLM Experience:** Can't complete any manual retopo task
- **User Impact:** Major advertised feature (manual retopology) unusable
---
## 6. Functionality Gap Analysis
### 6.1 What Was Intended (BDD Specifications)
**Vision:** Complete manual retopology toolkit leveraging:
- **Draw X-ray:** Visual clarity overlay system
- **RetopoFlow:** Professional retopology add-on (5 tools)
- **Quad Remesher:** Automatic quad mesh generation
- **LoopTools:** Topology refinement operations (4 tools)
- **MACHIN3tools:** Surface-constrained editing
- **QuadWrap:** Cylindrical topology wrapping
**Use Case:** LLM-guided manual retopology workflows
```
User: "Help me retopologize this character's arm"
LLM: 1. Enable draw x-ray for clarity
2. Start RetopoFlow session
3. Use Contours tool for cylindrical loops
4. Use PolyStrips for muscle definition
5. Use LoopTools to refine spacing
6. Export result
```
### 6.2 What Was Delivered (Actual Code)
**Reality:** Non-functional facade
- MCP tools: 12/12 implemented ✓
- Python implementations: 12/12 complete ✓
- Input validation: 12/12 present ✓
- Error handling: 12/12 present ✓
- Docstrings: 12/12 comprehensive ✓
- Backend handlers: 0/12 implemented ✗
- **Functional tools: 0/12** ✗
**Gap:** 100% - Complete implementation disconnect
### 6.3 Incomplete Components
#### Missing in addon.py:
**1. Handler Methods (NOT IMPLEMENTED)**
```python
# Required but missing in addon.py:
def draw_xray_enable(self, opacity, color, strokes, snap_engine):
"""Enable Draw X-ray overlay in Blender viewport"""
# Implementation needed
def retopoflow_start(self, mode):
"""Initialize RetopoFlow add-on session"""
# Requires: RetopoFlow API integration
# Implementation needed
def quad_remesher_remesh(self, target_quads, adaptive_size, adaptive_quad_count, guides):
"""Invoke Quad Remesher add-on"""
# Requires: Quad Remesher API integration
# Implementation needed
# ... and 9 more handler methods
```
**2. Handler Registration (NOT ADDED)**
```python
# Required addition to addon.py line 253:
handlers = {
# ... existing handlers ...
"export_asset": self.export_asset,
# NEW HANDLERS NEEDED:
"draw_xray_enable": self.draw_xray_enable,
"retopoflow_start": self.retopoflow_start,
"rf_contours_draw": self.rf_contours_draw,
"rf_polystrips_draw": self.rf_polystrips_draw,
"rf_strokes_fill": self.rf_strokes_fill,
"rf_brush": self.rf_brush,
"quad_remesher_remesh": self.quad_remesher_remesh,
"looptools_relax": self.looptools_relax,
"looptools_space": self.looptools_space,
"looptools_bridge": self.looptools_bridge,
"looptools_flatten": self.looptools_flatten,
"surface_slide_toggle": self.surface_slide_toggle,
"quadwrap_wrap": self.quadwrap_wrap,
}
```
**3. Third-Party Add-on Integration (NOT STARTED)**
Each handler needs to:
- Check if the required add-on is installed
- Access the add-on's API (if available)
- Fall back to operator calls if no API
- Handle add-on-specific errors
- Return structured results
**Example complexity - retopoflow_start:**
```python
def retopoflow_start(self, mode):
# Check if RetopoFlow is installed
if "retopoflow" not in bpy.context.preferences.addons:
return {"error": "RetopoFlow add-on not installed"}
# Access RetopoFlow API (if exists)
# or invoke operators: bpy.ops.cgcookie.retopoflow()
# Configure settings for retopology
# Handle RetopoFlow-specific state
# Return success with object names
return {"retopo_object": "...", "source_object": "..."}
```
### 6.4 Tools That Don't Serve Retopology Use Case
**All 12 tools serve the retopology use case appropriately:**
- Draw X-ray: Visualization for retopo work ✓
- RetopoFlow tools: Core retopology operations ✓
- Quad Remesher: Automated starting point ✓
- LoopTools: Manual topology refinement ✓
- Surface Slide: Precise surface-constrained editing ✓
- QuadWrap: Cylindrical topology creation ✓
**Finding:** Tool selection is appropriate, but implementation is incomplete.
---
## 7. Specific Blocking Issues
### 7.1 Severity 1 (CRITICAL - Immediate Blockers)
#### Issue 1.1: No Backend Handlers
- **Location:** `addon.py` lines 204-253
- **Severity:** CRITICAL
- **Impact:** 100% of features 16-27 non-functional
- **Details:** Handler dictionary missing all 12 new command types
- **Fix Required:** Implement 12 handler methods + register in handlers dict
- **Lines of Code:** Estimated 500-1000 LOC needed
- **Complexity:** HIGH - requires third-party add-on integration
#### Issue 1.2: No Add-on Availability Checks
- **Location:** N/A (not implemented)
- **Severity:** CRITICAL
- **Impact:** Tools will crash if add-ons not installed
- **Details:** No detection of RetopoFlow, Quad Remesher, MACHIN3tools, QuadWrap
- **Fix Required:** Pre-flight checks before invoking each tool
- **Example:**
```python
def quad_remesher_remesh(self, ...):
if "quad_remesher" not in bpy.context.preferences.addons:
return {"error": "Quad Remesher add-on not installed. Install from Blender Market."}
```
#### Issue 1.3: No Operator Integration
- **Location:** N/A (not implemented)
- **Severity:** CRITICAL
- **Impact:** Even if handlers exist, no way to invoke add-on functionality
- **Details:** Third-party add-ons expose functionality via operators
- **Fix Required:** Map tool parameters to operator calls
- **Example:**
```python
def looptools_relax(self, iterations, preserve_shape):
# Requires: bpy.ops.mesh.looptools_relax()
# Must be in EDIT mode with selection
# Must handle errors if LoopTools disabled
```
### 7.2 Severity 2 (HIGH - Functional Limitations)
#### Issue 2.1: Missing Prerequisites Documentation
- **Location:** BDD feature files
- **Severity:** HIGH
- **Impact:** Users won't know what to install
- **Details:** Feature files state "Given RetopoFlow 4 is installed" but no installation guide
- **Fix Required:** Document add-on requirements in README
- **Recommended:**
```markdown
## Third-Party Add-on Requirements
Features 16-27 require the following Blender add-ons:
- RetopoFlow 4 (Features 16-22): https://github.com/CGCookie/retopoflow
- Quad Remesher (Feature 18): https://exoside.com/quadremesher/
- LoopTools (Features 23-25): Built-in, must be enabled
- MACHIN3tools (Feature 26): https://machin3.io/MACHIN3tools/
- QuadWrap (Feature 27): https://github.com/...
```
#### Issue 2.2: No Error Recovery Guidance
- **Location:** Tool implementations
- **Severity:** HIGH
- **Impact:** LLM doesn't know how to fix failures
- **Details:** Error messages don't suggest next steps
- **Example Current:**
```
Error: Unknown command type: retopoflow_start
```
- **Example Better:**
```
Error: RetopoFlow integration not available.
This tool requires:
1. RetopoFlow 4 add-on installed
2. Handler implementation in Blender add-on
Status: Feature not yet functional (missing backend handlers)
```
#### Issue 2.3: Hardcoded String Parameters
- **Location:** Multiple tools (path, line_set identifiers)
- **Severity:** MEDIUM
- **Impact:** LLM must guess valid values
- **Details:** Tools like `rf_polystrips_draw(path="cheekbone")` use freeform strings
- **Issue:** No validation of path names
- **Fix Required:** Either:
- Document common path names in docstrings
- Implement path validation in handlers
- Make paths optional with auto-detection
**Example - rf_polystrips_draw (line 1344):**
```python
def rf_polystrips_draw(
ctx: Context,
path: str, # <- What are valid values?
strip_width: float = 0.08,
segments: int = 12,
bridge_existing: bool = True
) -> str:
"""
Draw PolyStrips along feature lines for loop control.
Parameters:
- path: Feature path identifier (e.g., 'cheekbone', 'upper_eyelid')
^ Examples provided but not validated
"""
```
### 7.3 Severity 3 (MEDIUM - Usability Issues)
#### Issue 3.1: No Tool State Tracking
- **Location:** All stateful tools (RetopoFlow session, Surface Slide toggle)
- **Severity:** MEDIUM
- **Impact:** LLM can't query current state
- **Details:** Tools like `surface_slide_toggle(enabled=True)` change state but no way to check current state
- **Fix Required:** Add query tools:
```python
@mcp.tool()
def get_retopoflow_status() -> str:
"""Check if RetopoFlow session is active"""
@mcp.tool()
def get_surface_slide_status() -> str:
"""Check if Surface Slide is currently enabled"""
```
#### Issue 3.2: Missing Undo Context
- **Location:** All tools that modify geometry
- **Severity:** MEDIUM
- **Impact:** Can't undo tool operations individually
- **Details:** Blender undo system not properly contextualized
- **Fix Required:** Each handler should use:
```python
bpy.ops.ed.undo_push(message=f"BlenderMCP: {tool_name}")
```
#### Issue 3.3: No Progress Feedback
- **Location:** Long-running tools (quad_remesher_remesh)
- **Severity:** LOW
- **Impact:** LLM and user don't know if tool is working
- **Details:** Quad Remesher can take minutes on complex meshes
- **Fix Required:** Consider async patterns or progress callbacks
---
## 8. Recommendations (Prioritized)
### Priority 1: UNBLOCK BASIC FUNCTIONALITY
**8.1 Implement Stub Handlers (1-2 days)**
Create minimal handlers in addon.py to test the connection:
```python
# Add after line 253 in addon.py
def draw_xray_enable(self, opacity, color, strokes, snap_engine):
"""Stub: Enable Draw X-ray overlay"""
return {
"status": "not_implemented",
"message": "Draw X-ray feature requires handler implementation",
"requested_params": {
"opacity": opacity,
"color": color,
"strokes": strokes,
"snap_engine": snap_engine
}
}
# Repeat for all 12 tools...
# Update handlers dict at line 253:
handlers.update({
"draw_xray_enable": self.draw_xray_enable,
"retopoflow_start": self.retopoflow_start,
# ... add all 12 ...
})
```
**Benefit:** Tools stop returning "Unknown command type" and start providing actionable feedback.
**8.2 Add Add-on Detection (1 day)**
```python
def check_addon_installed(addon_id):
"""Check if a Blender add-on is installed and enabled"""
return addon_id in bpy.context.preferences.addons
def get_available_integrations():
"""Return which third-party integrations are available"""
return {
"retopoflow": check_addon_installed("retopoflow"),
"quad_remesher": check_addon_installed("quad_remesher"),
"looptools": check_addon_installed("mesh_looptools"),
"machin3tools": check_addon_installed("MACHIN3tools"),
"quadwrap": check_addon_installed("quadwrap")
}
# Add new MCP tool in server.py:
@mcp.tool()
def get_available_integrations(ctx: Context) -> str:
"""Check which third-party retopology add-ons are installed"""
result = blender_connection.send_command("get_available_integrations")
# Format as user-friendly message
```
**Benefit:** LLM can query what's available before attempting to use tools.
### Priority 2: IMPLEMENT CORE FUNCTIONALITY
**8.3 Implement LoopTools Integration (2-3 days)**
Start with LoopTools since it's built-in to Blender (just needs enabling):
```python
def looptools_relax(self, iterations, preserve_shape):
"""Relax selected loops using LoopTools"""
# Validate add-on enabled
if "mesh_looptools" not in bpy.context.preferences.addons:
return {"error": "LoopTools add-on not enabled. Enable in Preferences > Add-ons"}
# Validate context
if bpy.context.mode != 'EDIT_MESH':
return {"error": "Must be in Edit Mode"}
obj = bpy.context.active_object
if not obj or obj.type != 'MESH':
return {"error": "Active object must be a mesh"}
# Count selected vertices before
bm = bmesh.from_edit_mesh(obj.data)
selected_verts_before = len([v for v in bm.verts if v.select])
if selected_verts_before == 0:
return {"error": "No vertices selected"}
# Execute LoopTools operator
try:
# Set LoopTools preferences
lt = bpy.context.scene.looptools
lt.relax_iterations = iterations
# Note: preserve_shape may not be directly exposed
# Execute operator
bpy.ops.mesh.looptools_relax()
return {
"vertex_count": selected_verts_before,
"iterations": iterations,
"preserve_shape": preserve_shape
}
except Exception as e:
return {"error": f"LoopTools Relax failed: {str(e)}"}
```
**Benefit:** 4/12 tools functional (looptools_relax, looptools_space, looptools_bridge, looptools_flatten).
**8.4 Document Add-on Requirements (1 day)**
Update README.md with comprehensive installation guide:
```markdown
## Advanced Retopology Features (16-27)
BlenderMCP includes integration with professional retopology add-ons.
### Required Add-ons
| Feature | Add-on | Installation | License |
|---------|--------|--------------|---------|
| 16-22 | RetopoFlow 4 | [GitHub](https://github.com/CGCookie/retopoflow) | GPL |
| 18 | Quad Remesher | [Exoside](https://exoside.com/quadremesher/) | Commercial |
| 23-25 | LoopTools | Built-in (must enable) | GPL |
| 26 | MACHIN3tools | [machin3.io](https://machin3.io/MACHIN3tools/) | Free |
| 27 | QuadWrap | Status unclear | TBD |
### Installation Steps
1. Install required add-ons via Blender Preferences > Add-ons
2. Enable each add-on
3. Test availability: Ask Claude to run `get_available_integrations()`
```
### Priority 3: ENHANCE UX & ROBUSTNESS
**8.5 Add State Query Tools (1 day)**
```python
@mcp.tool()
def check_retopoflow_session(ctx: Context) -> str:
"""Check if RetopoFlow session is currently active"""
result = blender_connection.send_command("check_retopoflow_session")
if result.get("active"):
return f"RetopoFlow session active. Tool: {result.get('active_tool')}"
else:
return "No active RetopoFlow session"
```
**8.6 Improve Error Messages (1 day)**
Update all tool implementations to include fix suggestions:
```python
if "error" in result:
error_msg = result['error']
# Add context-specific help
if "not installed" in error_msg.lower():
error_msg += "\n\nTo fix: Install the required add-on from Preferences > Add-ons"
elif "not enabled" in error_msg.lower():
error_msg += "\n\nTo fix: Enable the add-on in Preferences > Add-ons"
elif "edit mode" in error_msg.lower():
error_msg += "\n\nTo fix: Switch to Edit Mode by selecting an object and pressing Tab"
return f"Error: {error_msg}"
```
**8.7 Add Integration Tests (2-3 days)**
Create test suite that validates:
```python
# tests/test_features_16_27.py
def test_handler_registration():
"""Verify all 12 tools have handlers registered"""
required_handlers = [
"draw_xray_enable",
"retopoflow_start",
# ... all 12
]
# Load addon handlers
from addon import BlenderMCPServer
server = BlenderMCPServer()
for handler_name in required_handlers:
assert handler_name in server.handlers, \
f"Handler '{handler_name}' not registered"
def test_tool_discovery():
"""Verify MCP tools are discoverable"""
# Query MCP server for available tools
# Verify all 12 tools appear in list
def test_basic_invocation():
"""Verify tools don't crash on invocation"""
# For each tool, invoke with default params
# Verify receives structured response (not crash)
```
### Priority 4: FUTURE ENHANCEMENTS
**8.8 Create Retopology Workflow Orchestration**
Add high-level tool that guides LLM through complete workflow:
```python
@mcp.tool()
def start_retopology_workflow(
ctx: Context,
source_object: str,
target_polycount: int = 10000,
workflow_type: str = "CHARACTER"
) -> str:
"""
Initialize complete retopology workflow with appropriate tool chain.
Workflow types:
- CHARACTER: Face loops, limbs, organic forms
- HARD_SURFACE: Sharp edges, planar surfaces
- ENVIRONMENT: Mixed organic/hard surface
Returns recommended workflow steps for the LLM to execute.
"""
```
**8.9 Add Workflow State Persistence**
Allow resuming interrupted workflows:
```python
@mcp.tool()
def save_retopology_checkpoint(ctx: Context, name: str) -> str:
"""Save current retopology workflow state"""
@mcp.tool()
def load_retopology_checkpoint(ctx: Context, name: str) -> str:
"""Resume saved retopology workflow"""
```
---
## 9. Architectural Assessment Summary
### Strengths
1. **Excellent Code Organization** - Clean separation of concerns maintained
2. **Comprehensive Documentation** - All tools well-documented for LLM consumption
3. **Proper Error Handling** - Consistent validation and error messages
4. **Following Patterns** - New code matches established architectural patterns
5. **Good BDD Coverage** - All features have clear acceptance criteria
6. **Appropriate Tool Selection** - Chosen add-ons are industry-standard
### Weaknesses
1. **Zero Functional Tools** - Complete disconnect between MCP and Blender layers
2. **No Integration Testing** - Tools implemented without backend validation
3. **Missing Prerequisites Check** - No detection of required add-ons
4. **Incomplete Documentation** - Installation requirements not documented
5. **No State Management** - Can't query tool states or workflow progress
### Risk Assessment
| Risk Category | Level | Mitigation |
|---------------|-------|------------|
| User Frustration | CRITICAL | Implement stub handlers immediately |
| Project Credibility | HIGH | Document current limitations clearly |
| Development Waste | HIGH | Add integration tests before new features |
| LLM Confusion | HIGH | Improve error messages with fix suggestions |
| Add-on Compatibility | MEDIUM | Test against specific add-on versions |
---
## 10. Conclusion
### Mindful Verdict
**"The garden has been beautifully planned and the seeds carefully planted, but the irrigation system was never connected. The plants appear healthy from a distance, but upon closer inspection, nothing can grow without water."**
### Summary Statistics
- **Code Quality:** 8/10 (well-structured, well-documented)
- **Architectural Compliance:** 9/10 (follows patterns correctly)
- **Functional Completeness:** 0/10 (no tools work)
- **LLM Usability (Potential):** 9/10 (excellent docs)
- **LLM Usability (Actual):** 1/10 (all tools fail)
- **BDD Compliance:** 0/12 scenarios can pass
### Estimated Fix Effort
| Phase | Description | Effort | Priority |
|-------|-------------|--------|----------|
| 1 | Stub handlers + registration | 1-2 days | P0 - Critical |
| 2 | Add-on detection + docs | 1 day | P0 - Critical |
| 3 | LoopTools integration (4 tools) | 2-3 days | P1 - High |
| 4 | Draw X-ray integration | 2 days | P1 - High |
| 5 | RetopoFlow integration (5 tools) | 5-7 days | P2 - Medium |
| 6 | Quad Remesher integration | 2 days | P2 - Medium |
| 7 | MACHIN3/QuadWrap integration | 2-3 days | P3 - Low |
| 8 | Integration tests | 2-3 days | P1 - High |
| 9 | Enhanced error handling | 1 day | P2 - Medium |
| **Total** | **Complete features 16-27** | **18-28 days** | |
### Final Recommendation
**DO NOT** advertise features 16-27 as functional until:
1. Stub handlers implemented (Phase 1) - minimum viable communication
2. Add-on requirements documented (Phase 2) - user transparency
3. At least LoopTools integrated (Phase 3) - proof of concept
**DO** continue development following the existing architectural patterns, which are sound.
**DO** implement integration tests to catch these disconnects earlier in future development.
---
## Appendix: File References
### Files Reviewed
- `D:\repos\blender-mcp\ARCHITECTURE.md`
- `D:\repos\blender-mcp\README.md`
- `D:\repos\blender-mcp\src\server.py` (lines 1-1581)
- `D:\repos\blender-mcp\addon.py` (lines 1-200, 204-295)
- `D:\repos\blender-mcp\features\16_draw_xray.feature` through `27_quadwrap.feature` (12 files)
- `D:\repos\blender-mcp\src\retopo_tools\draw_xray.py`
- `D:\repos\blender-mcp\src\tools\integrations\retopoflow.py`
- `D:\repos\blender-mcp\src\tools\integrations\quad_remesher.py`
- `D:\repos\blender-mcp\src\tools\integrations\looptools.py`
- `D:\repos\blender-mcp\src\tools\integrations\machin3.py`
- `D:\repos\blender-mcp\src\tools\integrations\quadwrap.py`
### Key Line References
- **server.py:313-338** - Tool imports for features 16-27
- **server.py:1283-1559** - MCP tool wrapper registrations
- **addon.py:204-253** - Handler dictionary (MISSING entries for features 16-27)
- **addon.py:294** - Error path for unknown command types
---
**Report Generated:** 2025-11-11
**Architecture Guardian:** Read-Only Code Monk
**Repository:** D:\repos\blender-mcp
**Branch:** main
**Status:** Modified files detected (see gitStatus)
