orcaslicer-mcp

Let an AI assistant like Claude work with OrcaSlicer and your OrcaSlicer code.

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What is this? (plain version)

Claude and other AI assistants can only talk by default. An MCP server is a small helper program that gives them new abilities — like hands and eyes for a job.

This helper gives the AI two sets of abilities:

1. Work with your code. Look at your OrcaSlicer code, check what changed, read files, search the code, and check if your online tests passed.
2. Work with the slicer. Slice a 3D model into a print file, then read back how long it will take, how much filament it uses, and how many layers it has.

So instead of you clicking around, you can just ask: "Slice the Julia vase and tell me how long it takes," or "What changed in my code today?"

MCP stands for Model Context Protocol. It's just the name for the standard way AI apps plug into helper programs like this one.

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What you need first

You need these installed on your Windows PC. Each one is free.

Thing	Why you need it	Check it works
Python 3.10 or newer	This helper is written in Python.	Open a terminal and type python --version
Git	To download this helper and read your code history.	git --version
GitHub CLI (gh)	To check your online code and tests.	gh --version
OrcaSlicer	The slicer this helper drives.	Make sure it opens normally
An AI app	Claude Desktop or Claude Code (the thing you talk to).	—

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How to install (step by step)

1. Download this helper

Open a terminal and run:

git clone https://github.com/Diterex/orcaslicer-mcp.git
cd orcaslicer-mcp

2. Install the one Python package it needs

python -m pip install "mcp[cli]"

3. Find the full path to your Python

You'll need this in the next step. On Windows, run:

where python

Copy the first line it prints. It looks something like C:\Users\YOU\AppData\Local\Programs\Python\Python310\python.exe.

4. Tell your AI app about this helper

You add a few lines to your AI app's settings file. Below is the pattern. Replace the two paths with your paths (your Python from step 3, and the folder where you downloaded this helper).

"orcaslicer-mcp": {
  "type": "stdio",
  "command": "C:\\Path\\To\\python.exe",
  "args": ["C:\\Path\\To\\orcaslicer-mcp\\server.py"],
  "env": {}
}

Where does that go?

• Claude Desktop: in claude_desktop_config.json, inside the mcpServers section.

• Claude Code: in .claude.json, inside the mcpServers section. Or, easier, run this one command (put your real paths in):

  claude mcp add --scope user orcaslicer-mcp -- "C:\Path\To\python.exe" "C:\Path\To\orcaslicer-mcp\server.py"
  

Tip: use double backslashes (\\) in the JSON file, like the example shows.

5. Restart your AI app

Close it fully and open it again. That's it — the new abilities are ready.

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How to use it

Just talk to your AI normally. Here are things you can try:

• "What branch am I on and what's changed?"
• "Show me my last 5 commits."
• "Did my latest tests pass on GitHub?"
• "List the test models I can slice."
• "Slice the Julia vase model and tell me the print time and filament weight."
• "Read the print file we just made and summarize it."

The AI picks the right ability for what you asked.

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Settings you can change (optional)

Good news: it finds most things by itself. It looks for OrcaSlicer in the usual places (and on your system PATH), and it finds your code folder if you run it from inside your OrcaSlicer folder. So for slicing, you usually don't set anything.

One thing to set for the code tools: if you want the "work with your code" tools (git, GitHub), point it at your OrcaSlicer folder with ORCA_FORK_DIR. That's the only setting most people need.

You set any of these inside the "env" part of the config from step 4:

Setting	What it points to	Auto-detected?
ORCA_FORK_DIR	The folder with your OrcaSlicer code.	Only if you run it from inside that folder — otherwise set it.
ORCA_SLICER_EXE	The full path to orca-slicer.exe.	Yes (checks PATH + normal install spots).
ORCA_CORPUS_DIR	A folder with test models and profiles.	Defaults to the code's resources/profiles.
ORCA_OUTPUT_DIR	Where sliced files are saved.	Yes (~/.orcaslicer-mcp/out).
ORCA_INTEGRATION_BRANCH	The branch your work merges into.	Defaults to main.

Example (inside "env": { ... }):

"env": {
  "ORCA_FORK_DIR": "C:\\Users\\YOU\\code\\OrcaSlicer",
  "ORCA_SLICER_EXE": "D:\\Programs\\OrcaSlicer\\orca-slicer.exe"
}

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Is it safe?

Yes, by design. Some abilities can change things — like saving a commit, sending code to GitHub, or opening a pull request. Those never happen on their own.

The AI first shows you exactly what it would do and does nothing. It only goes through if you clearly say yes (the tool needs a confirm flag turned on). So the AI can't quietly push your code or open a request without you agreeing.

Also good to know: this helper runs on your computer with your permissions, the same as any program you start. Only install helpers you trust.

A few things it does to stay safe:

• Stays in bounds. Reading files, slicing, and reading print files are all limited to your OrcaSlicer folder, your model folder, and its output folder. It won't read or overwrite files elsewhere on your PC.
• No sneaky flags. Values you pass (branch names, search text, file paths) can't be turned into hidden command options.
• Point it at code you trust. For the code tools, set ORCA_FORK_DIR to your own OrcaSlicer folder rather than running it inside a folder you downloaded from someone else.

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The full list of abilities (tools)

Work with your code

Tool	What it does
orca_repo_info	Shows your branch, remotes, and how far ahead/behind you are.
orca_git_status	Shows what's changed right now.
orca_git_diff	Shows the exact line changes.
orca_git_log	Shows recent commits.
orca_branches	Lists all branches.
orca_checkout	Switches to (or makes) a branch.
orca_fetch_upstream	Gets updates from the original OrcaSlicer project.
orca_search_code	Searches your code for a word or pattern.
orca_read_file	Reads part of a file.
orca_gh_pr	Lists, views, or (with your OK) opens pull requests.
orca_gh_issue	Lists, views, or (with your OK) opens issues.
orca_ci_status	Checks if your online tests passed.
orca_commit	Saves a commit (only with your OK).
orca_push	Sends commits to GitHub (only with your OK).

Work with the slicer

Tool	What it does
orca_list_profiles	Lists your printer profiles and test models.
orca_slice	Slices a model into a print file.
orca_analyze_gcode	Reads a print file: time, filament, layers, cost.

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Works alongside OrcaSlicer's built-in helper

OrcaSlicer is adding its own built-in MCP helper (PR #12667) that controls the app while it's open — screenshots, the 3D view, live settings. That one and this one work well together:

• This helper works with your code and can slice without opening the app.
• The built-in one controls the open app (screenshots and the 3D view).

You can turn on both.

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License

MIT — free to use, change, and share. See LICENSE.