308 lines
9.0 KiB
Markdown
308 lines
9.0 KiB
Markdown
# FreeCAD MCP Server Comparison Analysis
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This document analyzes existing FreeCAD MCP server implementations to identify best practices and improvements for our architecture.
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## Existing Implementations
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### 1. [neka-nat/freecad-mcp](https://github.com/neka-nat/freecad-mcp) (380+ stars)
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**Architecture:**
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- XML-RPC server running inside FreeCAD (port 9875)
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- Queue-based GUI communication for thread safety
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- FastMCP-based MCP server connecting via XML-RPC
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**Key Features:**
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- `create_object()` supports Part::, Draft::, PartDesign::, Fem:: types
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- `get_view()` captures screenshots with multiple perspectives
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- `insert_part_from_library()` for part library access
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- Smart screenshot handling (detects unsupported views like TechDraw)
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**Strengths:**
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- Thread-safe queue system for GUI operations
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- Comprehensive object type support
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- Screenshot capabilities with view selection
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- Parts library integration
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**Weaknesses:**
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- XML-RPC only (no embedded/headless mode)
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- No macro development tools
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- Limited debugging capabilities
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---
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### 2. [jango-blockchained/mcp-freecad](https://github.com/jango-blockchained/mcp-freecad)
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**Architecture:**
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- 6 connection modes: Launcher, Server, Bridge, RPC, Wrapper, Mock
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- FastMCP 2.13.0+ with FastAPI integration
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- Multi-provider AI support (Claude, OpenAI, Google, OpenRouter)
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**Key Features:**
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- AppImage/AppRun launcher integration
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- Connection recovery mechanisms
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- Resource caching and performance diagnostics
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- Modern GUI addon with real-time diagnostics
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**Strengths:**
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- Most flexible connection options
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- Multi-AI provider support
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- Performance monitoring
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- Connection recovery/resilience
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**Weaknesses:**
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- Complex setup with many moving parts
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- Heavier dependency footprint
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---
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### 3. [contextform/freecad-mcp](https://github.com/contextform/freecad-mcp)
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**Architecture:**
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- Node.js-based MCP bridge (`working_bridge.py`)
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- AICopilot workbench integrated into FreeCAD
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- Cross-platform installer (`freecad-mcp-setup`)
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**Key Features:**
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- 13 PartDesign operations (Pad, Revolution, Fillet, Chamfer, etc.)
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- 18 Part operations (Primitives, Booleans, Transforms)
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- 14 View control tools
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- Automated installer with OS detection
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**Strengths:**
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- Most comprehensive CAD operation coverage
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- Excellent PartDesign/Part workbench integration
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- Easy installation process
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- Demo showcasing full workflow (house modeling)
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**Weaknesses:**
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- Node.js dependency adds complexity
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- Less focus on debugging/development workflows
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---
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### 4. [ATOI-Ming/FreeCAD-MCP](https://github.com/ATOI-Ming/FreeCAD-MCP)
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**Architecture:**
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- Server-client with stdio/TCP (port 9876)
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- GUI control panel inside FreeCAD
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- Macro-centric workflow
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**Key Features:**
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- Macro templates (default, basic, part, sketch)
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- Automatic import injection in macros
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- Macro validation before execution
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- View control (front, top, right, axonometric)
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- Log management and report browser
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**Strengths:**
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- Focus on macro development workflow
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- GUI panel for easy control
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- Automatic boilerplate injection
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- Comprehensive logging
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**Weaknesses:**
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- Macro-only focus (no direct object creation)
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- Windows-centric paths in documentation
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---
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### 5. [bonninr/freecad_mcp](https://github.com/bonninr/freecad_mcp)
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**Architecture:**
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- Simple socket-based server
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- Two primary tools: `get_scene_info` and `run_script`
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**Key Features:**
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- Comprehensive scene information retrieval
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- Arbitrary Python code execution
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- Minimal, focused API
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**Strengths:**
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- Simple, easy to understand
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- Full Python access via `run_script`
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- Lightweight
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**Weaknesses:**
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- Very minimal tool set
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- No specialized CAD operations
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---
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## Feature Comparison Matrix
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| Feature | neka-nat | jango | contextform | ATOI-Ming | bonninr | **Ours** |
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| ------------------- | -------- | ----- | ----------- | --------- | ------- | -------- |
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| Headless mode | No | Yes | No | No | No | **Yes** |
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| GUI mode | Yes | Yes | Yes | Yes | Yes | **Yes** |
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| XML-RPC | Yes | Yes | No | No | No | **Yes** |
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| Socket/TCP | No | Yes | No | Yes | Yes | **Yes** |
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| Embedded Python | No | No | No | No | No | **Yes** |
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| Screenshot capture | Yes | Yes | Yes | No | No | **Yes** |
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| Parts library | Yes | No | No | No | No | **Yes** |
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| Macro support | No | No | No | Yes | No | **Yes** |
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| PartDesign tools | Basic | Yes | Yes | Via macro | No | **Yes** |
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| Boolean operations | Yes | Yes | Yes | Via macro | No | **Yes** |
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| FEM support | Yes | No | No | No | No | **Yes** |
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| Multi-AI provider | No | Yes | No | No | No | No |
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| Connection recovery | No | Yes | No | No | No | **Yes** |
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| Thread-safe GUI ops | Yes | Yes | Unknown | Unknown | Unknown | **Yes** |
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| MCP Resources | No | No | No | No | No | **Yes** |
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| MCP Prompts | No | No | No | No | No | **Yes** |
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---
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## Key Learnings & Improvements for Our Architecture
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### 1. Communication Protocol
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**Learning:** neka-nat uses XML-RPC which is proven and reliable.
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**Improvement:** Support both XML-RPC (for compatibility) and JSON-RPC over sockets (simpler, more modern). Add embedded mode for true headless operation.
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### 2. Thread-Safe GUI Operations
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**Learning:** neka-nat's queue-based system is essential for GUI stability.
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**Improvement:** Implement similar queue system with Qt timer for main thread execution:
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```python
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# Queue-based GUI communication
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rpc_request_queue = queue.Queue()
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rpc_response_queue = queue.Queue()
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def process_gui_tasks():
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"""Execute queued operations on main GUI thread."""
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while not rpc_request_queue.empty():
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task = rpc_request_queue.get()
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result = task()
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rpc_response_queue.put(result)
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```
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### 3. Screenshot Capabilities
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**Learning:** neka-nat handles unsupported view types gracefully.
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**Improvement:** Add comprehensive view support with intelligent fallbacks:
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- Multiple view angles (Isometric, Front, Top, Right, etc.)
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- View type detection (skip TechDraw, Spreadsheet)
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- Configurable resolution and format
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### 4. Macro Development Focus
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**Learning:** ATOI-Ming's macro-centric approach is unique and valuable.
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**Improvement:** Add dedicated macro tools:
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- `create_macro` with templates
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- `validate_macro` for syntax checking
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- `run_macro` with parameter passing
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- Automatic import injection
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### 5. PartDesign Integration
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**Learning:** contextform has the most comprehensive PartDesign coverage.
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**Improvement:** Add specialized PartDesign tools:
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- Pad, Pocket, Revolution, Groove
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- Fillet, Chamfer
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- Hole (with standards support)
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- LinearPattern, PolarPattern
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- Mirrored
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### 6. Connection Resilience
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**Learning:** jango-blockchained has connection recovery mechanisms.
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**Improvement:** Add connection health monitoring and auto-reconnect:
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```python
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async def maintain_connection(self):
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"""Background task to maintain connection health."""
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while self._running:
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if not await self.is_connected():
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await self.reconnect()
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await asyncio.sleep(5)
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```
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### 7. Parts Library Integration
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**Learning:** neka-nat provides access to FreeCAD parts library.
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**Improvement:** Expose parts library with search and filtering.
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### 8. Comprehensive Logging
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**Learning:** ATOI-Ming has excellent logging with GUI browser.
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**Improvement:** Add structured logging with levels, rotation, and optional GUI viewer in plugin.
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---
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## Updated Architecture Decisions
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Based on this analysis, our architecture will:
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1. **Support 3 connection modes:**
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- Embedded (headless, in-process FreeCAD)
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- XML-RPC (proven, compatible with neka-nat addon)
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- JSON-RPC over socket (modern, simpler)
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1. **Implement queue-based GUI thread safety** following neka-nat's pattern
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1. **Provide comprehensive tool coverage:**
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- Execution: Python, macros
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- Documents: create, open, save, list
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- Objects: create, edit, delete, query
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- PartDesign: pad, pocket, fillet, chamfer, patterns
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- Part: primitives, booleans, transforms
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- Export: STEP, STL, OBJ, FreeCAD native
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- View: screenshot, camera control
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1. **Add unique features:**
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- MCP Resources for document introspection
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- MCP Prompts for guided workflows
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- Macro development toolkit
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- Workbench-specific tools
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1. **Focus on developer experience:**
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- Debugging tools
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- Error introspection
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- Console history access
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- Constraint validation
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---
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## Sources
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- [neka-nat/freecad-mcp](https://github.com/neka-nat/freecad-mcp)
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- [jango-blockchained/mcp-freecad](https://github.com/jango-blockchained/mcp-freecad)
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- [contextform/freecad-mcp](https://github.com/contextform/freecad-mcp)
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- [ATOI-Ming/FreeCAD-MCP](https://github.com/ATOI-Ming/FreeCAD-MCP)
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- [bonninr/freecad_mcp](https://github.com/bonninr/freecad_mcp)
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