Orcaslicer MCP

OrcaSlicer MCP

Let Claude work alongside you in a real, running OrcaSlicer. It loads models, arranges the plate, tunes settings, slices, and reads the result back as numbers you can question: which feature ate the print time, what a setting actually does, whether a profile breaks your printer's physics. Every change lands in the GUI while you watch, so the slicer stays yours and you get better at it as you go.

This package is an MCP server: it bundles no model. It talks to OrcaSlicer, at an address you configure (localhost by default), and, when you use the printer tools, makes read-only requests to your 3D printer. It sends the printer no commands and uploads nothing to it. The model comes from your MCP client. If that client uses a hosted one, your conversation goes there as any chat does; your models, profiles, and gcode stay on the machine running the slicer. Point the client at a local model and nothing goes to a hosted service.

What it can do

Knowing what the settings mean

An offline settings reference ships with the package, carrying the authoritative label, tooltip, type, range, enum, and default for each key, so describe_setting, search_settings, and compare_settings answer from OrcaSlicer's own source instead of guessing. consult composes curated slicing knowledge and your saved notes by topic, symptom, or goal.

check_profile_physics is a deterministic gate. It overlays proposed changes on the live config, runs flow, temperature, geometry, and cooling math, then returns ok, warnings, or blocked. Accelerations your printer cannot reach and speeds past the flow ceiling get caught before they reach a print.

Settings

Read and write any of roughly 800 OrcaSlicer settings on the live config, for the whole plate or scoped narrower: get_config, set_config, find_config_keys, set_layer_height, set_height_range for a band of layers, and set_object_config for one object's overrides.

On a multi-filament setup, per-filament keys are read merged across every loaded slot but written one preset at a time, and selecting a preset discards unsaved overrides in every group. So make filament edits first and print edits second; docs/order-of-operations.md explains why and gives the sequence.

Presets

list_presets, select_preset, get_preset_config, edit_preset, save_preset, rename_preset, delete_preset. select_preset discards unsaved overrides in every group, not only the one switched; see docs/order-of-operations.md.

Slicing, and reading the result back

slice, slice_and_wait, apply_and_slice, cancel_slice, get_slice_status, get_slice_warnings, get_gcode.

get_slice_breakdown returns per-feature time, filament, and flow. OrcaSlicer shows the same information in the legend beside its preview, sized for a screen; this returns it as numbers an assistant can compare and act on:

role                    time      share   filament   mean flow

inner_wall 5m 41s 30.8% 6.43 g 16.0 mm3/s outer_wall 3m 19s 18.0% 3.20 g 13.6 mm3/s sparse_infill 3m 07s 17.0% 3.57 g 17.0 mm3/s internal_solid_infill 2m 01s 11.0% 1.72 g 11.8 mm3/s bridge 52s 4.7% 0.26 g 4.4 mm3/s support_interface 36s 3.2% 0.52 g 12.3 mm3/s overhang_perimeter 28s 2.5% 0.13 g 3.7 mm3/s internal_bridge 21s 1.9% 0.45 g 19.9 mm3/s top_surface 19s 1.7% 0.29 g 12.5 mm3/s brim 12s 1.1% 0.21 g 14.7 mm3/s bottom_surface 7s 0.7% 0.10 g 11.8 mm3/s 18m 24s 16.89 g

It answers which feature is eating the time without slicing repeatedly to find out. A prediction_check rides along and flags any role where the profile's requested speed got throttled at the flow ceiling.

compare_slices slices the current plate under several named variants and returns one comparison, so "what does layer height actually cost me?" is a single question rather than four manual slices. It applies each variant over your original config, restores it when done, and hands back a verdict plus a table with every delta already worked out:

Recommended: 0.4mm - fastest with no warnings.

variant time filament vs 0.4mm (baseline) 0.3mm 8h 10m 41.0 g +1h 30m (+22%), -7.0 g (-15%) 0.4mm * 6h 40m 48.0 g baseline 0.5mm 5h 20m 53.4 g -1h 20m (-20%), +5.4 g (+11%) 0.6mm 4h 35m 57.1 g -2h 05m (-31%), +9.1 g (+19%) thin-wall warning

It only crowns a winner when one variant genuinely beats the rest on time, filament, and warnings; when they trade off, it names the fastest, the lightest, and where the warnings landed, and leaves the choice in front of you. Pass detail=True for the per-feature split of each variant.

Models and the plate

load_model (.stl, .obj, .3mf, plus .step and .stp on fork v2.3.2-mcp.3 and later), list_objects with each object's world-space bounding box and an on_plate flag, transform_object, duplicate_object, delete_object, arrange_plate, auto_orient, check_placement, diagnose_plate, get_job_status.

Several plates

list_plates, add_plate, select_plate, delete_plate and move_object_to_plate build a multi-plate project the way the toolbar does: one part per plate, each sliced on its own. Slicing, G-code, renders and job status always act on the current plate, so select a plate before you slice it. list_objects reports the plate each object sits on. Keep arrange_plate away from a layout like this: OrcaSlicer's arrange packs every unlocked plate together again. These need fork v2.4.2-mcp.13 or later.

CANVAS slots. With an Elegoo Centauri Carbon 2 and a CANVAS unit, get_printer_slots reads the trays (label, status, material, colour), get_filament_slot_mapping shows which tray each filament of the current plate would use, and set_filament_slot_mapping changes that choice. Only the mapping can be changed. Nothing is sent: OrcaSlicer's Send dialog opens pre-filled and you still click Send. For any other printer, or when the printer cannot be reached, the reply is supported: false with a reason and a message. These need fork v2.4.2-mcp.14 or later.

Project files

save_project writes the project as a .3mf exactly as File > Save does: plates, placement, per-object and per-plate settings, height ranges, slot presets and colours, unsaved overrides. It never replaces an existing file unless told to. open_project brings a saved project back as File > Open Project does (not a geometry import), open_recent_project does the same for an entry of File > Recent, and new_project starts over. OrcaSlicer's prompts ("save changes?", "keep modified presets?") would hang a remote caller, so each one is answered from an argument: if_unsaved is fail by default, so nothing is lost without being asked for. get_project and get_status report the project's name, path and whether there is something to save, so an agent knows when to save.

Around the files themselves: list_recent_projects shows File > Recent and whether each file still exists, forget_recent_project tidies that list, browse_projects lists the .3mf files in a folder on the OrcaSlicer host, move_project_file renames or moves a project file (the window follows when it is the open project), and delete_project_file removes one from disk, permanently, never the open project's own file. These need fork v2.4.2-mcp.15 or later.

Plate renders

render_plate hands back a PNG, so the assistant can look instead of inferring from coordinates. A rotation reads instantly as a picture and barely at all as three Euler angles. Seven camera angles cover iso, top, front, left, right, rear, and bottom. Use frame="plate" to stand back for the whole bed, or frame="object" to lean in on the part. Requires fork v2.3.2-mcp.4 or later.

describe_plate answers the same questions as numbers and one sentence per object, computed from the sliced G-code: how the part stands (flat, tilted, or on an edge or corner, from first-layer contact against its widest layer), the first-layer footprint as islands, where overhang extrusions concentrate by height band, where support stands and where it touches the part, and which side the seams sit on, checked against seam_position. It exists because an assistant reads a sentence more reliably than a picture. Copies of an object are aggregated; the islands still show each copy's contact patch. On a plate of three tilted bracket copies it reads: "bracket.stl (3 copies) stands on an edge or corner: first-layer contact is 5% of its widest layer, in 3 islands of about 50 mm2 each. Overhang extrusions concentrate at Z 0 to 10 mm. Support is present from Z 0.4 to 56.8 mm, standing in 3 places and touching the part in 7 zones. Seams align on the +Y side (91%), matching seam_position=back."

Live state and memory

get_status and watch_events report what the slicer is doing now. remember persists machine, user, and project facts for later sessions, as plain local files in ~/.orcaslicer-mcp/notes/, relocatable with ORCA_MCP_NOTES_DIR.

Printer feedback

get_printer_status reports what the printer is doing now: idle, heating, printing, paused, finished, or stopped by a fault, with nozzle and bed temperatures, the job's progress and time left, and any problems the printer reports in its own words. Common Klipper messages come with a short plain-English hint. wait_for_printer waits until the printer has heated, started extruding, or finished the first layer, or until the job ends (completed, cancelled or failed). OctoPrint reports no extrusion, so there waiting for printing means waiting until the job is running with the heaters at temperature. It returns early if the printer reports a fault, or if the job ends before the point it waits for, as when you cancel a print while it heats. It rides out brief network drops: after three failed checks in a row it stops and reports "Lost contact with the printer" along with the last status it saw. list_print_history lists recent jobs with how each one ended, how long it took against the slicer's estimate, and, for failed ones, the printer's reason while its console still holds it. check_printer_match compares the active profile with the printer's own settings: nozzle size, bed size, speed and acceleration limits, maximum temperatures, and firmware retraction. A check without enough data comes back as unknown, and when nothing could be checked the answer says so instead of reporting a match. Asking for more acceleration than Klipper's max_accel earns a warning because current Klipper accepts the higher value when the G-code sets it (M204 or SET_VELOCITY_LIMIT), so the printer acc