ankusdrive

AnkusDrive

A CLI + MCP server that drives FreeCAD through its Python API so LLMs (and humans at a terminal) can design mechanical parts and run FEM simulations without clicking through the GUI.

Why

FreeCAD exposes almost everything it does through a Python API — create documents, build sketches, extrude solids, mesh them, run CalculiX/Elmer FEM solves, read back stress/displacement fields. But that API lives inside FreeCAD's embedded Python (freecadcmd), which is awkward to call from anywhere else. AnkusDrive wraps it behind two surfaces:

• CLI — one-shot commands (ankusdrive run script.py, ankusdrive box --w 10 --d 20 --h 5 -o part.FCStd) for scripts, CI, and quick iteration.
• MCP server — 280+ structured tools (new_document, add_primitive, boolean_op, pad, add_gear, fem_new_analysis, fem_run, fem_results) so an LLM agent can model, inspect, and simulate iteratively. Beyond core CAD/FEM this now spans a broad simulation surface (thermal, CFD/CHT, EM, acoustics, FSI, injection molding, granular/DEM, optics, multibody) and a design-control layer (item/part numbers, recipes, variant families, lifecycle/revision, ECO change orders, versioned interfaces).
• Multi-agent orchestration — a host-side reference layer that lets a team of agents partition one product into components, build them in parallel, and merge the pieces back together with the joints actually fitting (see Multi-agent design).

Target environment

• FreeCAD 1.1.x. The freecadcmd binary is auto-discovered per-OS (macOS .app bundle, Linux /usr/bin etc., Windows C:\Program Files\FreeCAD 1.1\bin\freecadcmd.exe — version-globbed); override via $ANKUSDRIVE_FREECADCMD or rely on PATH. Run ankusdrive doctor to see exactly what resolved.
• Bundled Python, ccx (CalculiX), and gmsh already ship inside every FreeCAD install — the macOS .app, the Linux package, and the Windows bin\ — so core CAD + structural FEM work on all three with no extra install.
• Host-side rendering needs Pillow and numpy; both are installed by AnkusDrive as regular pip deps.
• One optional exception: drawing PDF/SVG export (export_drawing) renders inside FreeCAD's bundled Python, so it needs reportlab + svglib installed there — see Drawing export (PDF/SVG). DXF export and everything else leave FreeCAD's Python untouched.

Setup

AnkusDrive is a pip-installable package; FreeCAD itself is the only thing you install separately. The host-side dependencies (mcp, Pillow, numpy) come along with the install. freecadcmd is launched as a subprocess and uses its own bundled Python — AnkusDrive doesn't touch it.

# 1. Install FreeCAD 1.1.x from https://www.freecad.org/
#    (macOS: drag to /Applications; Linux: distro package or AppImage;
#     Windows: run the installer — default C:\Program Files\FreeCAD 1.1)

# 2. Install AnkusDrive. Pick one:
pipx install ankusdrive                                       # from PyPI — isolated app, `ankusdrive` on PATH
pip install ankusdrive                                        # or into an env you manage yourself
# unreleased main, or for development from a clone:
pipx install git+https://github.com/gchen19/AnkusDrive.git
git clone https://github.com/gchen19/AnkusDrive.git && cd AnkusDrive
python3 -m venv .venv && .venv/bin/pip install -e .         # `.venv/bin/ankusdrive`

# 3. Smoke-test that the worker can reach FreeCAD, and see the full setup report
ankusdrive ping        # → ping=pong freecad=1.1.1
ankusdrive doctor      # per-item FreeCAD + solver checklist with the exact fix each

On Windows, don't follow the block above by hand — there is one scripted path that does all of it including the MCP registration: Windows quickstart (PowerShell).

AnkusDrive is published on PyPI at pypi.org/project/ankusdrive; the distribution roadmap beyond it (marketplace listings, hosted transport) is tracked in epic #303; the original phase plan is kept as a design record at docs/archive/PUBLISHING_PLAN.md.

Windows quickstart (PowerShell)

Windows is a first-class target (core CAD + CalculiX FEM run natively against a stock FreeCAD 1.1 install), and the whole core install is one script — venv, pinned dependencies, doctor, and the MCP registration line with resolved absolute paths:

# 1. Install FreeCAD 1.1.x from https://www.freecad.org/ (default C:\Program Files\FreeCAD 1.1).
#    Nothing needs to go on PATH — AnkusDrive globs the versioned install dir itself.

# 2. Clone and run the core installer. Windows PowerShell 5.1 is enough; no admin needed.
git clone https://github.com/gchen19/AnkusDrive.git
cd AnkusDrive
powershell -ExecutionPolicy Bypass -File scripts\install-core.ps1

That creates .venv, installs AnkusDrive with the pins that matter (notably mcp<2 — mcp 2.x installs cleanly and then breaks ankusdrive mcp), verifies the resolved mcp/numpy/Pillow, runs ankusdrive doctor + ankusdrive ping, completes a real MCP stdio handshake, and finally prints your registration block. Useful switches: -Python 'C:\Program Files\Python313\python.exe' to pick an interpreter, -Extras mbd,fluids for the pip-wheel solver families, -Persist to write the FreeCAD path into %APPDATA%\ankusdrive\config.toml (MCP hosts launch with a minimal environment, so a $env: set in your terminal will not reach them).

3. Register it with your MCP host. The script prints these with your real paths filled in — a GUI host doesn't inherit your shell PATH, so the absolute path matters:

# Claude Code
claude mcp add ankusdrive -- C:\Users\you\AnkusDrive\.venv\Scripts\ankusdrive.exe mcp

# Claude Desktop: %APPDATA%\Claude\claude_desktop_config.json
#   { "mcpServers": { "ankusdrive": {
#       "command": "C:\\Users\\you\\AnkusDrive\\.venv\\Scripts\\ankusdrive.exe",
#       "args": ["mcp"] } } }

Then restart the host; you should see the ankusdrive__* tools appear.

Supported Python: 3.10 – 3.14 (3.14 verified end-to-end on Windows 11 — pip install, MCP stdio handshake, and ankusdrive ping → freecad=1.1.1). The script checks your interpreter before pip runs, so a too-new CPython says so instead of failing inside the resolver.

Optional solvers (SU2, Elmer, PrusaSlicer, WSL-backed OpenFOAM) come afterwards via scripts\install-solvers.ps1. Full per-solver reality, the test suite, and the WSL2 route: docs/WINDOWS.md.

Ubuntu 24.04+ / containers (apt has no FreeCAD)

FreeCAD was dropped from Ubuntu 24.04's universe repo, so apt install freecad finds no candidate there, and upstream's snap/flatpak both fail in a container or sandboxed agent environment (no snapd session, no FUSE). The path that works everywhere is the official AppImage, extracted:

scripts/install-freecad-appimage.sh          # or: scripts/install-solvers.sh freecad

It downloads the pinned release AppImage, checks its SHA-256, unpacks it with --appimage-extract (a userspace squashfs unpack — no FUSE, no root, no snapd, which is why it works in a container), symlinks freecadcmd, freecad, ccx and gmsh into /usr/local/bin, and then live-verifies the result with ankusdrive ping plus a real CalculiX solve (ankusdrive fem cantilever). Without a writable /opt it installs to ~/.local/opt/freecad instead; --prefix / --bindir override both, --appimage FILE reuses a download you already have.

The symlink step is optional: AnkusDrive also probes /opt/freecad/squashfs-root/usr/bin (and ~/.local/opt/freecad*/…) directly, so a hand-extracted AppImage in either prefix is auto-discovered. ccx and gmsh ride along inside the AppImage, so structural FEM works off this one download.

Telling AnkusDrive where FreeCAD lives

AnkusDrive auto-discovers freecadcmd in this order: $ANKUSDRIVE_FREECADCMD, then shutil.which(...) on PATH (trying freecadcmd, FreeCADCmd, and freecad.cmd), then a per-OS list of standard install locations:

OS	Auto-discovered locations (newest version wins)
macOS	/Applications/FreeCAD.app/Contents/Resources/bin/freecadcmd
Linux	/usr/bin, /usr/local/bin, /snap/bin/freecad.cmd, extracted AppImage under /opt/freecad*/squashfs-root/usr/bin or ~/.local/opt/freecad*/…, ~/.local/bin
Windows	C:\Program Files\FreeCAD *\bin\freecadcmd.exe (version-globbed), C:\Program Files (x86)\…, %LOCALAPPDATA%\Programs\FreeCAD *\bin\…

So a stock installer on any of the three needs no configuration. For a non-default install, point AnkusDrive at the binary directly:

export ANKUSDRIVE_FREECADCMD=/path/to/freecadcmd            # macOS/Linux

$env:ANKUSDRIVE_FREECADCMD = "D:\Apps\FreeCAD\bin\freecadcmd.exe"   # Windows

ankusdrive doctor prints which of the three layers (env / PATH / auto) actually resolved FreeCAD, plus every candidate it checked — the fastest way to debug a "FreeCAD not found" on a new box.

Drawing export (PDF/SVG)

export_drawing builds 2-D mechanical drawings (multi-view PDF/SVG/DXF with dimensions) entirely headless. DXF uses FreeCAD's own writer and needs nothing extra. PDF and SVG are composed and rasterised with reportlab + svglib, and because that runs inside the worker — FreeCAD's bundled Python, not the host venv — the two packages must be installed into FreeCAD's Python:

# Resolve FreeCAD's bundled Python from freecadcmd itself (portable across the
# macOS .app, a Linux distro package, and an extracted AppImage). freecadcmd
# prints a startup banner after the script output, so match a marker line
# rather than taking the last line:
printf 'import sys; print("DPREFIX="+sys.prefix)\n' > /tmp/_fcprefix.py
FREECAD_PREFIX="$(freecadcmd /tmp/_fcprefix.py 2>/dev/null | sed -n 's/^DPREFIX=//p')"
FREECAD_PY="$FREECAD_PREFIX/bin/python"      # some builds: $FREECAD_PREFIX/bin/python3

# Pin svglib<1.6 — newer svglib pulls rlPyCairo -> pycairo, a native build we
# don't use (our drawings are line art, no gradients).
"$FREECAD_PY" -m pip install reportlab "svglib<1.6"

# Verify:
"$FREECAD_PY" -c "import reportlab, svglib; print('drawing export ready')"

Without this, export_drawing still produces .dxf; .pdf/.svg raise a clear ModuleNotFoundError. FreeCAD already bundles Pillow (reportlab needs it), so no separate install is required.

Wiring it into an MCP host

The MCP server speaks stdio. Point your host at the ankusdrive binary and let it run the mcp subcommand.

Claude Desktop — add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "ankusdrive": {
      "command": "ankusdrive",
      "args": ["mcp"]
    }
  }
}

If ankusdrive isn't on the host process's PATH, use an absolute path — e.g. /Users/<you>/.local/bin/ankusdrive (pipx default) or /absolute/path/to/AnkusDrive/.venv/bin/ankusdrive (clone+venv).

Claude Desktop, one click — download ankusdrive-<version>.mcpb from the latest release and open it. Claude Desktop sets up its Python environment with uv, so no pipx step is needed — FreeCAD 1.1 still is. The install dialog has one optional field, the FreeCAD command path, for a FreeCAD that auto-discovery cannot find.

Claude Code — register once:

claude mcp add ankusdrive -- ankusdrive mcp

Other hosts (Cursor, Continue, custom MCP clients) — same shape: stdio transport, command = ankusdrive, args = ["mcp"].

After restarting the host, you should see 280+ ankusdrive__* tools become available. If startup hangs or the host reports a closed connection, run ankusdrive ping directly — that exercises the same worker boot path with cleaner error messages.

Tool families (toolsets). Every tool definition takes up the client's context, and all 281 come to roughly 114k tokens. Tools are grouped into families you can switch on and off: core (always on), drawings, fem, components, sheet_metal, assembly, intent, manufacturing, hand_calcs, simulation, plm, rendering.

• pip / pipx / uvx / clone: every family is on unless you set ANKUSDRIVE_TOOLSETS, e.g. ANKUSDRIVE_TOOLSETS=drawings,fem,simulation, or toolsets = "..." in config.toml.
• Claude Desktop extension: core, drawings and fem are on by default (~31k tokens); turn others on in the extension's settings.

setup_status lists the families that are off and exactly how to enable each one.

run_script executes Python the agent writes, with full access to your files and processes. It's controlled by ANKUSDRIVE_ALLOW_RUN_SCRIPT (env, or allow_run_script in config.toml):

• pip / pipx / uvx / clone: allowed unless set to false.
• Claude Desktop extension: off by default; turn it on in the extension's settings.

When it's off, the tool isn't offered at all, and setup_status says how to enable it.

Simulation solvers & review-video demos

The base install (FreeCAD + pip install ankusdrive) covers geometry, the analytic oracles, and the MCP surface. The heavy simulation families each shell out to an external solver, discovered at runtime by ankusdrive/solvers.py ($ANKUSDRIVE_<SOLVER>_PATH → PATH → standard install dirs). A family whose solver is absent degrades to a clean {ok: false, reason, install} dict instead of crashing — check what currently resolves with ankusdrive doctor (cross-platform, no server boot needed), the solve_capabilities MCP tool, or the install script's list. The install script installs the pip-wheel solvers and provisions the native ones — scripts/install-solvers.sh on Linux/macOS (apt/conda + source builds), and scripts/install-solvers.ps1 on Windows (pip extras + portable SU2/Elmer/PrusaSlicer downloads; CalculiX auto-detected from FreeCAD's bundle).

Persistent config: every ANKUSDRIVE_* path can instead live in ~/.config/ankusdrive/config.toml (%APPDATA%\ankusdrive\config.toml on Windows; ANKUSDRIVE_CONFIG overrides): freecadcmd = "..." at top level, one lowercased key per solver var under [solvers] (su2_path, elmer_path, openfoam_bashrc, ...). Env vars still win when set; the file is the layer that survives an MCP host's minimal launch environment. ankusdrive doctor reports the file and which layer resolved each value.

Platform note: the solver discovery layer is fully cross-platform (per-OS install dirs, Windows PATHEXT/.exe, env overrides), so ankusdrive doctor gives an honest report on macOS/Linux/Windows. The pip-wheel families (MBD, topology, optics, fluids) install identically everywhere. The native-binary families differ by OS — CalculiX ships inside every FreeCAD install; SU2 and PrusaSlicer have good Windows/macOS binaries; Elmer has a portable Windows zip but no macOS binaries; the OpenFOAM-backed families (CFD, FSI, injection molding) still rely on a Linux shell + linker glue and are Linux/WSL/Docker for now. See docs/WINDOWS.md and docs/MACOS.md for the full per-solver reality and setup on each OS.

The review-video demos under scratch/ turn a solver result into a GIF a human can watch — the real exported geometry in motion with the matching oracle overlaid on the frame (written to artifacts/). Each needs its family's solver plus matplotlib, and the CFD one needs meshio (on top of the base numpy/Pillow):

pip install matplotlib meshio        # frame rendering + reading OpenFOAM's VTK output

Review-video demo (scratch/…)	Solver it drives	Install
dog_clutch_cad_sim.py — rigid-body contact via p.vhacd	PyBullet (pip wheel)	pip install 'ankusdrive[mbd]'
meshing_gears_video.py — MBD gear train	PyBullet (pip wheel)	pip install 'ankusdrive[mbd]'
modal_shape_video.py — FEM modal shapes	CalculiX ccx (FreeCAD FEM)	apt install calculix-ccx (Linux); FreeCAD finds ccx on PATH
thermal_field_video.py — transient thermal field	Elmer	apt install elmerfem-csc; ensure ElmerSolver on PATH (or set ANKUSDRIVE_ELMER_PATH)
cfd_field_video.py — CFD field (lid-driven cavity)	OpenFOAM + meshio	OpenFOAM via apt/conda, then source <install>/etc/bashrc (or set ANKUSDRIVE_OPENFOAM_BASHRC); pip install meshio

All of them also use FreeCAD for the geometry/meshing, so run each with the same interpreter that launches the worker — e.g. .venv/bin/python3 scratch/cfd_field_video.py.

Optics

Two optics engines sit behind the MCP surface, in two licensing/runtime lanes:

Lane	Tools	Engine	Install
Sequential — lens design + optimization	optics_lens_design, optics_lens_optimize, optics_raytrace	optiland / rayoptics (MIT/BSD, in-process)	pip install 'ankusdrive[optics]' — or scripts/install-solvers.sh optics
Non-sequential — tracing through STL solids	optics_solid_trace	KrakenOS (GPL-3.0, out-of-process only)	pip install 'ankusdrive[optics_gpl]' — or scripts/install-solvers.sh optics_gpl

The sequential engines import in-process, so install the optics extra into the same interpreter that launches the worker (like the other wheels). The non-sequential engine is GPL-3.0 and is therefore never imported by AnkusDrive — it runs in a separate subprocess (ankusdrive/optics_gpl_runner.py), the same arm's-length boundary used for the GPL Elmer/OpenFOAM binaries. The worker locates a Python that can import KrakenOS automatically (from where the wheel is installed); override with ANKUSDRIVE_OPTICS_GPL_PYTHON=/path/to/python. Because of that isolation the GPL extra is opt-in: the no-argument install-solvers.sh run installs only the permissive extras and prints how to add optics_gpl. Rendered examples for both lanes (lens layout, spot diagram, optimization, prism TIR, and a ball-lens spherical-aberration study) live in examples/optics_gallery/ — regenerate with .venv/bin/python examples/optics_gallery.py (and …_3d.py, optics_ball_lens.py), or bootstrap everything in one shot (installs both lanes, then renders every figure):

scripts/install-solvers.sh --optics-gallery

Architecture sketch

 ┌────────────┐      ┌────────────┐      ┌──────────────────────┐
 │  MCP host  │ ───► │ AnkusDrive   │ ───► │  freecadcmd worker   │
 │  (Claude)  │      │ (Python)   │ IPC  │  (long-lived Python) │
 └────────────┘      └────────────┘      └──────────────────────┘
       ▲                    ▲                        │
       │                    │                        ▼
       └── CLI user ────────┘               .FCStd / .inp / .vtk

Key decision: long-lived worker with JSON-over-stdin/stdout, not subprocess-per-call. FreeCAD startup is ~1–2s; re-paying that per tool call is unacceptable for an interactive agent. The worker is a small Python loop launched under freecadcmd, reading commands, dispatching to handlers, returning structured results (including object IDs so follow-up calls can reference created geometry).

FreeCAD API surface we care about

Notes gathered from the scripting docs and the FEM Python tutorial:

Core (App):

• App.newDocument(name) / App.ActiveDocument / doc.recompute() / doc.save(path)
• doc.addObject("Part::Box", "name") — typed object creation; properties set after (box.Height = 5)
• doc.supportedTypes() for introspection; obj.TypeId, obj.isDerivedFrom("Part::Feature")

Modeling:

• Part — makeBox, makeCylinder, makeSphere, boolean cut/common/fuse, fillets, lofts (OpenCASCADE under the hood)
• Draft — 2D primitives, move, arrays
• Sketcher + PartDesign — parametric sketch-driven solids (most "real" mechanical design happens here)
• FreeCAD.Vector, Placement for positioning

FEM (ObjectsFem + femtools):

• ObjectsFem.makeAnalysis(doc, "Analysis") — container
• makeSolverCalculixCcxTools / makeSolverElmer — solver objects with tunables (GeometricalNonlinearity, ThermoMechSteadyState, …)
• makeMaterialSolid — assign YoungsModulus, PoissonRatio, Density
• Constraints: makeConstraintFixed, makeConstraintForce, makeConstraintPressure, makeConstraintDisplacement, contact/tie/spring, thermal
• Mesh: makeMeshGmsh + femmesh.gmshtools.GmshTools(...).create_mesh() (or Netgen)
• Run: femtools.ccxtools.FemToolsCcx().run()
• Results: iterate analysis.Group for Fem::FemResultObject; read .DisplacementVectors, stress fields

Headless invocation:

• freecadcmd script.py — runs script then exits
• freecadcmd with no args — interactive Python REPL (what the worker will drive)
• --console, -M <moddir>, -P <pypath>, --pass <args>, FreeCAD.ConfigGet(...) for env info
• FreeCADGui is not available headless — keep design logic in App/Part/Fem only

How an agent reaches FreeCAD: three layers

AnkusDrive exposes FreeCAD through three layers, each with a different audience and a different cost-of-use. Knowing which layer a feature lives in tells you how to invoke it.

Layer 1 — typed MCP tools (the agent surface)

280+ first-class MCP tools span the core mechanical-design surface, a broad engineering-analysis / simulation surface, and a design-control (PLM) layer. They have validated parameters, structured returns, and stable handles for chaining. This is the happy path — what an agent uses for things people do every day.

Domain	What's covered
Document lifecycle	new_document, open_document, save_document, list_documents, set_active_document, close_document, restart_worker
Geometry primitives	add_primitive (box/cyl/sphere), boolean_op, export_shape (STEP/IGES/BREP/STL)
Selection (stable refs)	list_faces, list_edges, query_faces, resolve_face, resolve_edge, register_handle, verify_feature
PartDesign	make_body, make_datum_plane, make_sketch, add_sketch_geometry, add_sketch_constraint, add_sketch_external, close_sketch, pad, pocket, revolve, hole, loft, sweep, helix, partdesign_fillet, partdesign_chamfer, linear_pattern, polar_pattern, mirrored, thickness, draft
Direct modeling & feature ops	fillet_edges, chamfer_edges, shell_solid, add_rib, engrave_text, oring_groove, transform, scale_shape, copy_shape
Parametric components	add_gear, add_rack, add_sprocket, add_pulley, add_spring, add_fastener, add_bearing, add_thread, list_thread_options
Metrology & inspection	measure_distance, measure_angle, bounding_box, check_shape, section_view, min_clearance, envelope_check, interference_check
Generic property access	get_object, set_property
Functional intent & invariants	annotate_face, list_face_roles, classify_face_sides, check_airtight_path, declare_intent, verify_intent
Performance contracts	declare_performance, verify_performance — a quantitative spec ("Cd ≤ 0.30 at 30 m/s", "Δp ≤ 50 Pa", "first mode ≥ 200 Hz") persisted on the part and re-proved after every edit, with a three-state verdict: a measurement whose uncertainty band straddles the limit is indeterminate (escalate), never a pass. The contract is consulted at the gates (#261): merge_assembly, substitutability_check and component_contract_check read the last recorded verdict, so an unmet spec blocks a merge and an unverified one is reported as its own outcome rather than passing silently
Design-space studies (DOE)	study_submit — sweep recipe/tool parameters over a full grid or a Latin hypercube and keep the WHOLE search as a table, not just the last point. A response is any AnkusDrive tool + a metric path (including a whole verify_performance verdict, so points stay comparable across fidelity tiers); screening responses evaluate inline, solver responses fan out concurrently behind one collector job. Sampling is deterministic from seed, so re-submitting a crashed or widened study re-runs only the new points and reports the rest as cache hits
Optimize to a spec	optimize_submit — vary bounded parameters until every constraint passes, then report whether it was proven. A bounded Nelder-Mead (derivative-free; there is no adjoint through a CFD solve) over the same objective/constraint mapping the contract layer uses, with a screen→solver fidelity ladder. Two rules come from the contract layer: an indeterminate constraint is a measurement problem, not a failed step (it neither attracts nor repels the search), and convergence is not proof — a margin narrower than its own uncertainty band is reported unproven, however tidily the simplex converged
Assembly & interfaces	make_assembly, add_part, list_assembly_parts, merge_assembly, publish_interface, interface_align_check, assembly_lock, assembly_lock_check, bom_extract
Drawings (TechDraw, headless)	make_drawing_page, add_projection_group, add_section_view, add_thumbnail, add_dimension, add_annotation, add_feature_note, add_gdt_callout (feature control frames), set_title_block, fit_page, export_drawing (PDF/SVG/DXF), plus completeness/legibility gates drawing_gate, drawing_legibility
Inspection (first-article)	balloon_drawing (revision-stable balloon numbering), inspection_plan (characteristic list with a measurement method per row, by the gauge-maker's 10:1 rule), fai_report (AS9102-Form-3-shaped CSV/SVG/PDF — not a certified submission); drawing_gate(require_ballooned=True) makes a ballooned print a release requirement
Release packages (vendor / RFQ)	release_package — the one-call deliverable bundle for an item at a revision: STEP + drawings (PDF/SVG/DXF) + recursive BOM + inspection package + a blake2b-checksummed manifest. Gated before anything is written: the item must be in a releasable lifecycle state (or draft=True, which watermarks every artifact PRELIMINARY), drawing_gate must pass for every included page, and the title block's part number / revision / material must match the items registry — a mismatch is a failure with a naming diff, never a silent fix. Byte-reproducible (the same revision re-releases to identical checksums), stamps the ECO into the manifest and the print, and rfq=True adds quantity breaks + the cost_estimate rollup while dropping internal-only artifacts
Off-the-shelf parts (buyability)	catalog_search (what standard components exist, in which sizes and stocked lengths), catalog_nearest (snap a wanted size to a real one — asked for an M4×13 it answers 12 and 16), catalog_check, standard_part_designate (canonical designations: ISO 4762 M4×12 A2, 608-2RS, AS568-214 NBR70, stamped on the part at creation), designation_check, bom_extract(orderable=True) (per-line stocked / not_stocked with alternatives)
Visual feedback	render_view, render_views (8 preset views, multi-view sheets), render_photoreal / render_photoreal_submit (Blender studio scene with per-part appearance for whole assemblies, or the FreeCAD Render add-on renderers; renderer="auto"), render_capabilities
FEM (FreeCAD/CalculiX/Elmer)	fem_new_analysis, fem_set_solver, fem_set_material, fem_set_nonlinear_material, fem_add_constraint (fixed/force/pressure/displacement/temperature/heatflux/initial_temperature), contact_setup, fem_mesh, fem_mesh_refinement, fem_modal, fem_buckling, fem_run, fem_results, fem_result_probe (stress/disp/temp at a point or face), fem_modal_results, fem_buckling_results, fem_thermal_results, plus the legacy fem_cantilever_demo
Engineering oracles & hand-calcs	machine elements (gear_rating, bearing_life, belt_drive, spring_check, bolted_joint_check, press_fit_stress, seal_check), structural (beam_modal, beam_buckling, plate_check, hertz_contact, elastica_deflection, plastic_collapse, random_vibration, harmonic_response), durability (fatigue_check, fracture_check, creep_flag, wear_estimate), thermal (thermal_lumped, thermal_transient_1d, thermal_composite_wall, h_estimate), tolerance/GD&T (tolerance_stackup, fit_check, fit_class, gdt_check)
Simulation families (external solvers, async)	screens + full solves that shell out to OpenFOAM/Elmer/CalculiX/openEMS/YADE/KrakenOS, most via a submit→poll job pattern: thermal/CHT (cht_channel_submit, cht_graetz_submit, thermal_transient_submit, thermal_radiation_submit), CFD (cfd_pipe_flow, cfd_body_drag, cfd_internal_flow_submit, cfd_external_flow_submit — including the virtual wind tunnel: hand it a solid and get Cd/Cl/Cm from an integrated force, gated against the sphere drag curve; every steady solve carries a trust block (convergence, checkMesh, measured y+) and cfd_mesh_independence_submit/grid_convergence put a Richardson/GCI error band on geometry with no analytic twin), EM (em_skin_depth, em_dc_resistance, em_field, em_conduction_submit, em_induction_submit, em_fullwave_submit), acoustics (acoustic_screen, acoustic_fem_submit, acoustic_radiation_submit), FSI (fsi_*), molding (molding_screen, molding_fill_submit, molding_warpage_submit), granular/DEM (granular_screen, dem_pack_submit, dem_flow_submit), optics (optics_lens_design, optics_lens_optimize, optics_raytrace, optics_solid_trace), multibody (mechanism_kinematics, mechanism_simulate_submit), topology (topology_optimize_submit, topology_to_solid)
Async jobs	job_status, job_result, job_list — poll/collect any *_submit long-running solve; solve_capabilities reports which solvers currently resolve
Materials & fluids	material_list, material_get, material_select, fluid_props — mechanical-property / molding / CoolProp thermophysical corpora behind a typed lookup
Sheet metal	sheet_base (base flange), sheet_flange / sheet_tab / sheet_hem (bends placed by stable edge tag), sheet_unfold (K-factor flat pattern + per-bend allowance/deduction, with the K in force and its source echoed into every result), sheet_refold (round-trip verification against the folded solid), sheet_flat_export (layered DXF — CUT / BEND_UP / BEND_DOWN, the file a laser/brake shop quotes from), sheet_check (min bend radius by material, min flange, hole-to-bend, refold collision)
Manufacturing & Design-for-X	dfm_check (also runs the sheet-metal press-brake rules when handed a sheet part), dfa_check, moldability_check, optics_moldability_check, pack_check, cost_estimate, slice_estimate, slice_gcode_submit, laminate_properties, drop_impact
CNC (machinability + machining time)	cnc_machinability_check (setups from the tool-approach census, undercuts, tool L/D, sharp/small internal corners, thin walls — pure geometry, no CAM engine), cnc_time_estimate (material-removal-rate model: removed volume / MRR plus finishing area, ±50 % against the flat table's ±100 %; feeds cost_estimate(machine_time_hr=…))
Tolerance ↔ cost	tolerance_cost_check (per-dimension IT grade, the cheapest process that holds it naturally, a relative cost index, and a flag when a dimension is tighter than the declared process can hold without a secondary operation), suggest_loosening (the loosest tolerance that works — greedy loosening, every step re-verified against tolerance_stackup's cpk); cost_estimate(tolerance_class=…) puts the same curve in the rollup
Design control / PLM	items & part numbers (items_new, items_validate, items_resolve, items_check_manifest), recipes (recipe, recipe_list, recipe_schema, recipe_validate), feature templates (feature_instantiate, feature_list, feature_schema, feature_validate), variant families (family_materialize, family_validate), lifecycle/revision (lifecycle_transition, lifecycle_editable, lifecycle_classify_change, lifecycle_apply_change), change control (eco_create, eco_validate, change_impact, where_used, baseline_create, baseline_verify), interface registry + substitutability (get_interface, substitutability_check), projects (scaffold_project, project_validate, project_check_references, project_resolve_manifest)
Operations	transaction_open, transaction_commit, transaction_abort

All tools return JSON; geometry-creating tools return a handle (e.g. pad_1) that subsequent calls reference. The heavy simulation families return a {ok: false, reason, install} dict (rather than crashing) when their solver isn't installed — see Simulation solvers.

Layer 2 — generic property reflection

For the long tail of "I just need to tweak this one property" without a dedicated tool:

• get_object(handle) — dump every entry in obj.PropertiesList with Quantities → float (mm/deg), Vectors → list, Placements → dict.
• set_property(handle, name, value) — set any single property by name.

Use this when a typed tool exists for the object kind but doesn't expose the exact property you need (e.g. Refine on a Pad, Sections ordering on a Loft, internal tunables on a CCX solver).

Layer 3 — run_script (the universal escape hatch)

For features that have no first-class MCP tool at all — e.g. Path workbench (CAM toolpaths), Surface workbench, Arch/BIM, Spreadsheet, TechDraw dimensions, contact/spring FEM constraints, B-spline sketcher operations, expression-engine bindings, anything in a workbench AnkusDrive doesn't wrap.

run_script(code='''
import Path
job = Path.Job.Create("Job", [_resolve("pad_1")])
__result__ = {"job_name": job.Name}
''')

Inside the script, the worker pre-injects: App / FreeCAD, Part, ObjectsFem, plus _register(prefix, obj) / _resolve(handle) / _handles so scripts can register new objects into the same handle registry that typed tools use. Set __result__ = ... to a JSON-serializable value to return data; print statements go to /dev/null.

The escape hatch costs more (the agent has to write FreeCAD Python) but makes the entire FreeCAD API reachable. The Phase 2 plan's "After Phase 2" section calls out which run_script patterns deserve promotion to typed tools — that's how the surface grows over time.

What the CLI is (and isn't)

The CLI is not the agent surface — it's a human-debugging + transport tool. Seven subcommands:

Command	Purpose
ankusdrive ping / version	Health check — boot a worker, prove FreeCAD is reachable
ankusdrive box / cylinder	Single-shot primitive → .FCStd (manual smoke tests)
ankusdrive export <in.FCStd> -o <out.step>	Headless format conversion
ankusdrive run <script.py>	Execute arbitrary FreeCAD Python in a live worker (set __result__ to return JSON)
ankusdrive mcp	Start the MCP server over stdio — this is how an MCP host launches AnkusDrive
ankusdrive fem cantilever	Run the built-in canned demo

Agents do not invoke the CLI. They speak MCP via stdio after the host has launched ankusdrive mcp. The CLI's job is (a) to start that server and (b) to give a human a way to poke at the worker without writing an MCP client.

Decision rule

Need	Use
Standard CAD/FEM operation	First-class MCP tool (Layer 1)
Tool exists but I need property X	get_object / set_property (Layer 2)
Workbench / API not wrapped at all	run_script (Layer 3)
Smoke test from a shell, or stand up MCP	CLI

Multi-agent design

The roadmap above is about deepening what one agent can do. The orchestration/ layer is about many agents sharing the work: split a product into components and subassemblies, build those in parallel (each agent cold, seeing only its own contract slice), then merge the whole back up with the joints actually fitting. The design is written up in docs/MULTI_AGENT.md; it targets partition + merge, not shared co-editing of one live document (a single worker = one App.ActiveDocument, so concurrent mutation is a non-goal for now).

Concurrent agents on one MCP server — workspaces. FastMCP runs sync tools in a thread pool, so a host can have several tool calls in flight at once. The server keeps a pool of named workspaces, each its own freecadcmd process with its own App.ActiveDocument and handle registry. Each concurrent agent claims its own workspace with use_workspace(name) at the start of its session; handles and documents do not cross workspaces. A client that never calls use_workspace sees the historical single-worker behavior byte-for-byte (everything routes to the default workspace). Worker.call() is internally serialized so two threads can never interleave the stdin/stdout protocol on one process. The pool is capped (ANKUSDRIVE_MAX_WORKSPACES, default 4) and idle workspaces are reaped (ANKUSDRIVE_WORKSPACE_IDLE_S, default 900s) so abandoned sessions don't leak processes; list_workspaces / close_workspace manage it.

The split of responsibilities is deliberate:

• AnkusDrive ships the thin, tool-agnostic primitives that make a merge verifiable — publish_interface (declare a component's mating frames), merge_assembly (combine component files into one assembly), and the gates that decide whether a merge is sound: interface_align_check (do published frames line up?), interference_check (do solids collide?), envelope_check (does it fit its bounding budget?), plus an assembly_lock / assembly_lock_check contract lockfile. These are real MCP tools usable by any host.
• orchestration/ is the host-side reference coordinator — explicitly not part of the ankusdrive package. Given a free-text brief it decomposes it into a validated manifest, fans out one builder agent per component, merge_assemblys them, reads the gates, and on failure renegotiates — re-dispatching only the components implicated by the failing gate — up to a round budget. It runs against a real Anthropic client or a scripted stub (ScriptedClient) for free dry runs; the merge and gates are real worker calls either way. Any host (Claude, another tool, a human) can use it, replace it, or ignore it — the only contract that matters is the manifest + the component files on disk.

How well partition+merge holds up is measured by a dedicated eval ladder (tests/test_multiagent_m1.py / _m2.py, runnable in CI) with hard-oracle merge gates and a single-agent baseline — see tests/MULTI_AGENT_EVAL.md. Early experiments have partition performing at or above the single-agent baseline on the harder toys.

Designs, not just parts — the design-control layer

Multi-agent orchestration partitions one product across a team. A separate axis makes a design (not just a part) something you can parameterize, vary, and evolve under control — the mechanisms a PLM/PDM workflow expects, mapped onto AnkusDrive's deterministic, headless, git-diffable grain. The keystone insight: the build recipe is the feature tree; the parameters are its inputs; regeneration is re-running the recipe — so AnkusDrive gets parametric regen and family tables without a live in-file expression engine. The full scoping and rationale is in docs/DESIGN_HIERARCHY.md; the agent-facing judgment lives in the design-modularly skill.

• Parametric hierarchy — recipes (recipe, recipe_validate) are named, declared-input build templates (AnkusDrive's PowerCopy/UDF and its intra-part parametric model); a relations DAG drives driven dimensions from master parameters by formula (pitch_d = module * teeth, arithmetic only — no iterative solve, no double-driving); feature templates (feature_instantiate) graft reusable features onto reference geometry by name; the typed units layer rejects dimensionally-wrong inputs at the door ("5 N" for a length is an error, not a silent mis-scale).
• Variant families — family_materialize expands a row × column design table into a set of variants deterministically, running the recipe per row and allocating part numbers in table order.
• Identity & lifecycle — items (items_new) give a part a stable part-number identity decoupled from its file path; a lifecycle state machine (lifecycle_transition: in_work → in_review → released → obsolete) enforces released-immutability, and a Form/Fit/Function predicate decides revision bump vs. new part number on a change.
• Change control — ECOs (eco_create) are first-class change records; where_used / change_impact compute blast radius over the dependency graph before you commit; baseline_create / baseline_verify pin reproducible snapshots.
• Versioned interfaces — an interface-type registry (get_interface, nema17_face@1-style named/versioned types) plus a Liskov substitutability_check gate enforce Form/Fit/Function compatibility as code, so a swapped part is verified to actually mate.
• Projects — scaffold_project + project_validate / project_check_references promote the multi-agent directory convention to a first-class project.json (manifest-of-manifests) with a master/skeleton single-source-of-truth slot and reference-integrity guards.

Like the merge gates, these are thin, deterministic, mostly FreeCAD-free primitives — the logic layers import and test without launching a worker.

Status

Phase 3 closed 2026-05-10 (v0.3.0). The core mechanical-design surface from Phase 2 (2026-04-25) is intact; Phase 3 layered intent-encoding APIs on top of it. Since then the tool surface has grown from ~100 to 280+ tools across several waves: a command-tier expansion (parametric components + direct feature ops + metrology), the multi-agent orchestration layer, a broad engineering-analysis + external-solver simulation surface (thermal/CFD/CHT/ EM/acoustics/FSI/molding/granular/optics/multibody), and a design-control (PLM) layer (items, recipes, variant families, lifecycle, ECO/change, versioned interfaces, projects).

• Worker + transport — long-lived freecadcmd worker, newline-JSON over stdio with stdio hygiene (FreeCAD C++ chatter redirected off the protocol fd).
• CLI — ping, version, box, cylinder, export, run, mcp, fem cantilever, plus top-level --version.
• MCP server — FastMCP over stdio, 280+ typed tools across document lifecycle, primitives, selection (face/edge tags), full PartDesign (sketcher + pad/pocket/revolve/hole/loft/sweep/helix/fillet/chamfer/pattern/mirror/thickness/draft), direct-modeling feature ops, parametric components, metrology/inspection, generic property reflection, mass properties, assembly + interface gates, TechDraw (incl. headless PDF/SVG/DXF export, dimensions, gates), multi-view + photoreal rendering, FEM (static + modal + buckling + thermal + nonlinear + result-probe), the engineering-analysis oracles and external-solver simulation families (sync + async *_submit/job_*), the materials/fluids corpora, Design-for-X / manufacturing checks, the design-control (PLM) layer, and transactions.
• Command tiers 1–3 — 21 new tools: parametric components (add_gear, add_rack, add_sprocket, add_pulley, add_spring, add_fastener, add_bearing, add_thread), direct feature ops (fillet_edges, chamfer_edges, shell_solid, add_rib, engrave_text, oring_groove, transform, scale_shape, copy_shape), and metrology/inspection (measure_distance, measure_angle, bounding_box, check_shape, section_view, min_clearance).
• Multi-agent orchestration — AnkusDrive ships the thin merge primitives + gates (publish_interface, merge_assembly, interface_align_check, envelope_check, assembly_lock/_check); the host-side reference coordinator (orchestration/) decomposes a brief, fans out per-component builders, merges, gates, and renegotiates. See Multi-agent design and docs/MULTI_AGENT.md.
• Phase 3 intent-encoding additions — direction='into_body'|'away_from_body' and through='wall'|'body' on pocket/hole (ray-cast wall depth handles hollow shells correctly); intended_for='print'|'machine'|'drawing' on hole drives ModelThread; verify_feature diffs actual-vs-expected volume change to catch silent failures; visibility hygiene at save hides consumed inputs; register_handle + run_script auto_register close the escape-hatch one-way trapdoor; list_thread_options surfaces the coupled ThreadType/ThreadSize enums dynamically; revolve has an OCCT pre-check that flags axis-coincident edges with an actionable error.
• Selection layer — list_faces / list_edges / query_faces / resolve_* produce stable geometric tags that survive edits; FEM constraints take tags directly.
• Rendering — host-side software rasterizer (ankusdrive/render.py) with per-pixel z-buffer (render_view / render_views return PNGs as MCP ImageContent), plus photoreal render_photoreal via the FreeCAD Render addon + an external renderer (POV-Ray / LuxCore / Appleseed / Cycles / OSPRay / PBRT). Support matrix, install, and limitations: docs/RENDERING.md.
• Simulation surface — engineering-analysis oracles (machine elements, structural, durability, thermal, tolerance/GD&T) plus external-solver families that shell out to OpenFOAM / Elmer / CalculiX / openEMS / YADE / KrakenOS, discovered at runtime by ankusdrive/solvers.py and degrading cleanly when absent. Long solves use an async submit→poll job pattern (*_submit + job_status/job_result/job_list). Catalog and result schemas: docs/SIMULATION_TOOLS.md; proof harness: docs/SIMULATION_EXAMPLES.md. Materials/fluids back these via material_* and fluid_props (mechanical-property / molding / CoolProp corpora).
• Design-control (PLM) layer — recipes + a relations DAG (parametric regen), feature templates, variant families from a design table, item/part-number identity, a lifecycle/revision state machine, ECO change records with where-used/impact + baselines, a versioned interface registry + Liskov substitutability gate, and project containers with reference-integrity guards. Scoping + rationale: docs/DESIGN_HIERARCHY.md. See Designs, not just parts.
• Tests — ~980 test functions across ~90 files (worker / MCP / CLI / render / determinism / edit stability / negative paths / perf / multi-agent / simulation families / molding / PLM layer), runnable via tests/run_all.sh (Linux/macOS) or tests/run_all.ps1 (Windows — single-interpreter, skips the Linux-only solver families; see docs/WINDOWS.md). Reliability harness (Layer A classification, B diff-detection, C agent-loop closure) is gated behind RUN_RELIABILITY=1; see tests/RELIABILITY.md.

See docs/ROADMAP.md for the Phase 1/2 per-slice record — a changelog of how the surface above was built, frozen at the close of Phase 2. Open work (FEM contact/spring/tie refinements, fully async fem_run, feature_tree introspection, deeper external-solver integrations) lives on the issue tracker, not in that file.

The committed showcase — every GIF, render, drawing and exported solid the docs point at, with the script that regenerates each one — is indexed in artifacts/README.md.

Open questions

• Error model: FreeCAD raises plain Python exceptions from C++; worker catches and serializes them, but stack context across the JSON boundary is still lossy.
• Async / concurrency: multi-doc shipped (list_documents / set_active_document / close_document), and the long-running external solvers run off the channel via the *_submit + job_* pattern, but the in-worker fem_run itself is still synchronous and blocks the MCP channel for the duration of a CalculiX/Elmer solve.
• macOS Gatekeeper / sandboxing: freecadcmd launched from a non-interactive context may hit quarantine issues. This has never been confirmed either way — tracked in #310, which will either document the fix or delete this caveat.

Privacy Policy

AnkusDrive runs entirely on your computer and collects nothing: no telemetry, no analytics, no accounts, and no network requests from its own code. It reads and writes only the files you point it at, plus its config file and temp working directories. Your MCP host (e.g. Claude Desktop) sends tool inputs and results to its AI model provider under the host's own policy. The full policy, including exactly what is stored where, is in PRIVACY.md.

Evaluating the Claude Desktop extension? The reviewer guide covers installation, a setup check, and three example prompts with expected results.

License

Licensed under the Apache License, Version 2.0. Contributions submitted to this project are licensed under the same terms (Apache 2.0 §5: inbound = outbound), which means contributors retain copyright but grant the project — and everyone downstream — a perpetual, irrevocable license to use their work, including a patent grant. The intent is to keep the project welcoming to contributors while ensuring nobody can later re-proprietize what they contributed.

The code is Apache-2.0; the name is not. Apache-2.0 §6 grants no trademark rights, so the AnkusDrive word mark and the brand assets in logo/ are covered separately — see TRADEMARKS.md for what you may do without asking (referring to the project, compatibility claims, redistribution, packaging, and forking all qualify) and NOTICE for the attribution a redistributor must carry.

References

• FreeCAD Scripting Basics
• Python scripting tutorial
• Start up and Configuration
• FEM Workbench
• FEM Tutorial Python — full cantilever example
• Model Context Protocol