This server is an MCP stdio server for building, editing, validating, rendering, and hand-off of Fritzing circuit designs and custom parts.
Search and inspect parts: search the 2663-part library plus local custom parts, and list connector IDs/names/types needed for wiring.
Create and edit sketches: create empty .fzz/.fz sketches, place parts with coordinates, wire connectors, move parts, set properties, and remove parts.
Inspect designs: dump sketch instances, positions, and wires as JSON.
Validate designs: run fritzing_check to ensure a sketch is valid before hand-off, and validate custom .fzp part files.
Render designs: headless-render sketches to SVG and PNG for visual inspection.
Create custom parts: generate fzp files plus 4 view SVGs from a JSON spec, optionally install them for the Fritzing app.
Hand off to humans: open sketches in the Fritzing GUI for review.
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type @ followed by the MCP server name and your instructions, e.g., "@fritzing-mcp search the part library for an LED and place it with a 220 ohm resistor, then wire them up and render the breadboard"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
MCP stdio server for building and editing Fritzing circuit designs (.fzz
sketches) and custom parts (.fzp/SVGs), wrapping the fz
CLI — a
stdlib-only Fritzing design toolkit for AI agents.
Parts
tool | purpose |
| search the 2663-part library + local custom parts |
| list a part's connector ids/names/types (needed before wiring) |
Sketch build
tool | purpose |
| create an empty |
| place a part (coordinates in px at 90 DPI) |
| wire two connectors ( |
| adjust instances |
| dump instances/wires as JSON |
Validation
tool | purpose |
| validate sketch (must pass before hand-off) |
| headless-render SVG/PNG for visual inspection |
Custom parts
tool | purpose |
| generate fzp + 4 view SVGs from a JSON spec, optionally install |
| validate a |
Hand-off
tool | purpose |
| open sketches in the Fritzing GUI for human review |
Related MCP server: schematic-mcp-bridge
Python ≥ 3.10, uv
The fz toolkit is bundled (fzkit/ + bin/fz + templates/) — no
second repo needed. FZ_BIN optionally points at a different launcher.
Runtime data from a local Fritzing app checkout, located via
FRITZING_APP_ROOT (default ~/code/fritzing/fritzing; render vars
FRITZING_APP/FRITZING_LIBS/FRITZING_PLUGINS still win): part search
needs <root>/parts/parts.db, custom-part authoring needs
parts/fzp_checker.py, and headless rendering needs the Fritzing binary
with Qt 6 libs plus ImageMagick for PNG. Sketch create/show/check work
without any of it.
uv sync # or: uv venv && uv pip install -e .Add to your MCP client config:
{
"mcpServers": {
"fritzing": {
"command": "uv",
"args": ["run", "--project", "/path/to/fritzing-mcp", "fritzing-mcp"]
}
}
}bun smoke.mjs # or: node smoke.mjsDrives the server over raw stdio MCP: searches parts, reads connectors,
builds a LED+resistor sketch (place/wire/move/props), validates it, and
renders the breadboard view. Prints SMOKE: N/N passed.
MIT
Validate a sketch: unique modelIndexes, resolvable moduleIds, every instance has >= 1 view, every wire endpoint connector exists on its target. MUST pass before handing a design off or opening it in the GUI.
Inputs: file (required). Returns: result
Generate a custom part (fzp + 4 view SVGs) from a JSON spec.
Custom parts must have all 4 views; restart Fritzing after --install (parts are scanned at startup).
Inputs: spec_path (required), out, install. Returns: result
Move a placed instance (omit x/y to read its current position).
Inputs: ref (required), file (required), x, y. Returns: result
Create an empty Fritzing sketch bundle.
Inputs: path (required), force. Returns: result
Open sketch(es) in the Fritzing GUI for human review.
Inputs: files (required). Returns: result
List a part's connector ids, names, and types (male/female/pad) as JSON.
Connector ids are what wire endpoints reference (e.g. "r1.connector1" -> "led1.connector1").
Inputs: module_id (required). Returns: result
Add a part instance to a sketch.
Coordinates are sketch pixels at 90 DPI (1 inch = 90 px; mm -> px = 90*mm/25.4). The placed instance's assigned ref is in the output — use it for wire/move/props.
Inputs: file (required), module_id (required), x, y, +3 more. Returns: result
Remove an instance from the sketch.
Inputs: ref (required), file (required). Returns: result
Headless-render sketch(es) to SVG (and optionally PNG via ImageMagick).
Writes _.svg/.png next to the target. The first render per session takes ~10 s (parts DB load). Read the PNG to visually inspect the design, then adjust positions/wires and re-render.
Inputs: target (required), png, view, density. Returns: result
Search the Fritzing parts library (2663 core parts + local custom parts).
Returns rows of moduleId title [family] (source). Call
fritzing_part_connectors with a result's moduleId before wiring it.
Inputs: query (required), limit, verbose. Returns: result
Set instance properties (name=value pairs).
Inputs: ref (required), file (required), props (required). Returns: result
Dump the sketch's instances (refs, moduleIds, positions, wires) as JSON.
Inputs: file (required). Returns: result
Validate a .fzp part definition file.
Inputs: fzp_path (required). Returns: result
Wire two part connectors together (creates the electrical ).
Inputs: file (required), ref_a (required), ref_b (required), view, +1 more. Returns: result
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
Loading tool schema changelog…
Scored across 14 tools
Most tools target distinct actions (move, remove, place, wire, render, etc.), but fritzing_check (validate a whole sketch) and fritzing_validate_part (validate a single .fzp part definition) share the 'validate' verb and could be briefly confused despite the descriptions distinguishing their scope.
Every tool uses the same snake_case verb/noun pattern with a uniform fritzing_ prefix (e.g. fritzing_place_part, fritzing_remove_part, fritzing_validate_part), making the set highly predictable.
14 tools is well-scoped for an EDA/sketch-editing server, covering distinct lifecycle stages (part discovery, sketch creation, placement, wiring, validation, rendering) without redundancy.
The surface covers sketch creation, part placement/movement/removal, wiring, property setting, rendering, and custom part creation, but lacks wire removal/editing and sketch deletion, leaving minor gaps agents must work around.
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