---
language:
- en
license: apache-2.0
tags:
- kicad
- pcb-design
- mcp
- tool-calling
- electronics
- eda
base_model: Qwen/Qwen3.5-4B
pipeline_tag: text-generation
model-index:
- name: KiCAD-MCP-Qwen3.5-4B
  results:
  - task:
      type: tool-calling
      name: Tool Selection
    metrics:
    - name: Accuracy
      type: accuracy
      value: 100
      verified: false
---

# KiCAD-MCP-Qwen3.5-4B

A fine-tuned Qwen3.5-4B model specialized for KiCAD PCB design assistance via the Model Context Protocol (MCP). Trained to select and invoke the correct tools from a 159-tool KiCAD MCP server covering schematic capture, PCB layout, DRC, export, library management, and more.

## Capabilities

- **Tool Selection**: Correctly identifies which of 159 KiCAD MCP tools to call based on natural language requests
- **Parameter Extraction**: Extracts component references, coordinates, net names, and other parameters from user requests
- **Multi-Step Reasoning**: Plans sequences of tool calls for complex PCB design tasks
- **Error Handling**: Interprets tool error responses and suggests fixes
- **Refusal**: Declines off-topic or destructive requests appropriately
- **Domain Knowledge**: Understands PCB design concepts (DRC rules, clearances, layer stacks, component placement)

## Tool Categories

The model was trained on a KiCAD MCP server with tools across these categories:

| Category | Tools | Examples |
|----------|-------|---------|
| Project | 5 | create_project, open_project, save_project |
| Schematic | 22+ | add_schematic_component, add_wire, connect_to_net, annotate_schematic |
| Board | 12 | set_board_size, add_layer, add_board_outline, get_board_2d_view |
| Component | 17 | place_component, move_component, rotate_component, find_component |
| DRC | 8 | run_drc, set_design_rules, get_drc_violations, check_clearance |
| Export | 8 | export_gerber, export_pdf, export_bom, export_3d |
| Routing | 14 | route_trace, add_via, add_copper_pour, route_differential_pair |
| Library | 8 | search_footprints, get_footprint_info, list_libraries |
| And more | ... | Symbol creation, JLCPCB integration, freerouting, UI management |

See `tool_schema.json` for the complete 159-tool schema with descriptions and parameter definitions.

## Usage

### With llama.cpp

```bash
# Download the model
huggingface-cli download empulse/KiCAD-MCP-Qwen3.5-4B-GGUF --local-dir ./model

# Run with llama-server (requires Qwen3.5 support — llama.cpp build from Feb 2026+)
llama-server \
  -m model/kicad-mcp-4b-sft-v3-bf16.gguf \
  -ngl 99 \
  --cache-type-k bf16 --cache-type-v bf16 \
  -c 4096 \
  --port 8080

# Query via OpenAI-compatible API
curl http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [
      {"role": "system", "content": "You are a KiCAD PCB design assistant with MCP tools."},
      {"role": "user", "content": "Run a DRC check on the board"}
    ],
    "temperature": 0.1
  }'
```

### Important Notes

- **GGUF format**: bf16 (full precision, 8.4GB). Quantize with `llama-quantize` if needed.
- **KV cache must be bf16**: Use `--cache-type-k bf16 --cache-type-v bf16` with llama.cpp. The Gated Delta Network architecture produces incorrect results with f16 cache.
- **Qwen3.5 support required**: llama.cpp builds from February 2026+ include Qwen3.5 GDN support (PR #19435).
- **Thinking mode**: The model uses `<think>...</think>` blocks for reasoning by default. Use `/nothink` prefix to disable.

## Training

- **Base model**: Qwen/Qwen3.5-4B
- **Architecture**: Gated Delta Network (GDN) — hybrid attention, not standard transformer
- **Method**: LoRA (rank 32, alpha 64) with two-phase training
  - Phase 1: Continual Pre-Training on domain-specific corpora (MCP protocol, KiCAD documentation, PCB design knowledge)
  - Phase 2: Supervised Fine-Tuning on tool-calling examples
- **Framework**: ms-swift 4.0.2 with DeepSpeed ZeRO-2
- **Hardware**: 2x NVIDIA RTX 3090 (48GB total)
- **Precision**: bfloat16 throughout (required for GDN architecture)

## Evaluation

| Category | Score |
|----------|-------|
| Tool Selection (10 tests) | 10/10 |
| No-Tool Response (2 tests) | 2/2 |
| Refusal (1 test) | 1/1 |
| Domain Knowledge (1 test) | 1/1 |
| **Total** | **14/14 (100%)** |

## Limitations

- Trained primarily on a specific KiCAD MCP server implementation — tool names and schemas may differ from other servers
- 4B parameter model — complex multi-step reasoning chains may be less reliable than larger models
- Domain knowledge is focused on KiCAD v10 and common PCB design patterns
- Not trained for vision/image tasks despite Qwen3.5's multimodal capabilities

## License

Apache 2.0