AutoCAD-MCP

Reliable AutoCAD automation for AI agents, with checked geometry, native 3D, and delivery evidence.

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AutoCAD-MCP connects Codex, Claude Code, Claude Desktop, Cursor, and any standard MCP client to full AutoCAD, AutoCAD LT, or a headless DXF backend. It is built for agents that must prove what they drew, not merely report that a script ran.

Why AutoCAD-MCP

• Checked writes: strict inputs, handle readback, requested/actual diffs, and document revisions. Native-worker transactions are atomic; compatibility COM/LISP paths report compensation limits instead of promising rollback they cannot prove.
• Useful CAD coverage: structured 2D drawing, layers, dimensions, topology DRC, native AutoCAD solids and booleans, bounded product features, motion screening, and fixed-camera review views.
• Delivery evidence: DWG/DXF/PDF/PNG outputs, exported-DXF re-audit, paper and scale verification, geometry digests, manifests, and SHA-256 hashes.
• Desktop friendly: AutoCAD stays taskbar-visible but minimized by default, drawing does not steal focus, and preview/PDF viewers are not launched.
• Client neutral: one stdio server for MCP clients; no Codex-only or Claude-only protocol.
• Honest limits: unsupported edge selection, shelling, exact continuous motion, and material rendering are reported explicitly instead of being simulated.

Try It Without AutoCAD

The headless demo creates a mechanical DXF, runs semantic DRC, renders a deterministic PNG, and prints the evidence:

git clone https://github.com/beiming183-cloud/AutoCAD-MCP.git
cd AutoCAD-MCP
uv sync
uv run python examples/headless_demo.py

Expected result: ok: true, six entities, and drc_status: PASS. Outputs are written to demo-output/ unless AUTOCAD_MCP_OUTPUT_ROOT is set.

Native AutoCAD Showcase

With a healthy, manually opened AutoCAD session, reproduce the promotional rotary actuator as editable native solids:

uv run python examples/generate_actuator_promo.py --record --pause 1.0

Recording mode activates AutoCAD once, creates a blank document, frames the planned model before the first write, pauses one second after each completed semantic step, and leaves the final document open. It deliberately skips PNG/PDF rendering and final rotation so no viewer or camera motion interrupts capture.

Choose a Backend

Backend	Runtime	Requires AutoCAD?	Validation feedback
Native worker	Windows Python	Full AutoCAD 2025/2026	Database transactions, revision events, feature IDs, native 2D/3D
File IPC compatibility	Windows Python	Full AutoCAD or AutoCAD LT 2024+	COM/LISP coverage, topology audit, PDF and PNG
ezdxf	Any platform	No (headless)	Structured audit + deterministic PNG

The server exposes 12 consolidated tools (drawing, entity, solid, product, layer, block, annotation, pid, transaction, view, job, system) over standard MCP stdio.

This edition is based on puran-water/autocad-mcp and retains its MIT license. Version 4.0 adds a native transactional worker, client-independent named-pipe protocol, external desktop supervisor, durable idempotency journal, and database-owned document revisions while retaining COM/LISP compatibility.

For startup failures caused by a damaged Python COM environment, an orphaned acad.exe, or Activity Insights permissions, use the Windows AutoCAD recovery runbook. system(operation="preflight") is read-only and does not start AutoCAD.

Prerequisites (File IPC backend)

• Windows 10/11 (the File IPC backend uses Win32 APIs for focus-free window messaging)
• Full AutoCAD or AutoCAD LT 2024+ on Windows - AutoLISP support was added to LT in 2024; full AutoCAD also uses the native COM path.
• Python 3.10+ (Windows native — not WSL Python)
• uv package manager (install guide)

The ezdxf headless backend works on any platform (Linux, macOS, WSL) for offline DXF generation without AutoCAD installed.

Quick Start

1. Clone and install

git clone https://github.com/beiming183-cloud/AutoCAD-MCP.git
cd AutoCAD-MCP
uv sync

2. Install the signed native worker (full AutoCAD 2025/2026)

The preferred industrial path is the .NET 8 worker under native/. It executes mutations under DocumentLock plus a native database transaction and publishes a current-user named pipe. Build, Authenticode-sign, verify, and install it with:

$env:AUTOCAD_MCP_AUTOCAD_DIR = "D:\cad\AutoCAD 2025"
.\native\scripts\build-plugin.ps1 `
  -AutoCADDir $env:AUTOCAD_MCP_AUTOCAD_DIR `
  -DotNet "D:\Codex\Tools\dotnet-sdk\dotnet.exe" `
  -CertificateThumbprint "YOUR_CODE_SIGNING_CERT_THUMBPRINT" `
  -Install

Installation refuses an unsigned DLL. Keep AutoCAD SECURELOAD enabled. The bundle loads at AutoCAD startup and writes its worker descriptor to %LOCALAPPDATA%\AutoCAD-MCP\workers.

For a stable desktop session, start the user-owned supervisor from an ordinary PowerShell window, not from an MCP client's sandbox:

$env:AUTOCAD_MCP_OUTPUT_ROOT = "D:\Codex\AutoCAD-MCP"
autocad-mcp-supervisor run `
  --acad-exe "D:\cad\AutoCAD 2025\acad.exe" `
  --window-mode quiet_minimized `
  --output-root "D:\Codex\AutoCAD-MCP"

The supervisor leaves AutoCAD visible in the taskbar but minimized, never opens PDF/PNG viewers, and leaves AutoCAD running when supervision stops. Use autocad-mcp-supervisor status from another terminal to inspect PID, HWND, heartbeat, fatal-window state, and native-worker discovery.

3. Load the LISP dispatcher for LT or compatibility fallback

Open AutoCAD or AutoCAD LT and load mcp_dispatch.lsp using APPLOAD:

1. Type APPLOAD in the AutoCAD command line
2. Browse to <repo>/lisp-code/mcp_dispatch.lsp
3. Click Load
4. You should see: === MCP Dispatch v4.0.0 loaded === and Ready for commands via (c:mcp-dispatch)

Tip: Add the file to your AutoCAD Startup Suite (in the APPLOAD dialog) so it loads automatically with every drawing.

4. Configure your MCP client

Add to your MCP client configuration (e.g. Claude Desktop claude_desktop_config.json):

{
  "mcpServers": {
    "autocad-mcp": {
      "command": "C:\\path\\to\\autocad-mcp\\.venv\\Scripts\\python.exe",
      "args": ["-m", "autocad_mcp"],
      "env": {
        "AUTOCAD_MCP_BACKEND": "file_ipc",
        "AUTOCAD_MCP_LISP_PATH": "C:\\path\\to\\autocad-mcp\\lisp-code\\mcp_dispatch.lsp"
      }
    }
  }
}

The same server command can be used in Claude Code project-level .mcp.json:

{
  "mcpServers": {
    "autocad": {
      "type": "stdio",
      "command": "C:\\path\\to\\autocad-mcp\\.venv\\Scripts\\python.exe",
      "args": ["-m", "autocad_mcp"],
      "env": {
        "PYTHONPATH": "C:\\path\\to\\autocad-mcp\\src",
        "AUTOCAD_MCP_BACKEND": "file_ipc",
        "AUTOCAD_MCP_NATIVE_PLUGIN": "auto",
        "AUTOCAD_MCP_AUTOSTART": "false",
        "AUTOCAD_MCP_VISIBLE": "true",
         "AUTOCAD_MCP_WINDOW_MODE": "preserve",
        "AUTOCAD_MCP_ACTIVATE_ON_DRAW": "false",
        "AUTOCAD_MCP_OUTPUT_ROOT": "D:/Codex/AutoCAD-MCP",
        "AUTOCAD_MCP_ACTIVITY_INSIGHTS_PATH": "D:/Codex/AutoCAD-MCP/activity-insights"
      }
    }
  }
}

Key points:

• The command must point to the Windows Python inside the project venv (not WSL python).
• AUTOCAD_MCP_BACKEND can be auto (tries File IPC, then falls back to ezdxf), file_ipc (recommended for engineering drawings), or ezdxf (headless only).
• Full AutoCAD prefers the native worker. COM/LISP remains a compatibility path; AutoCAD LT uses LISP/window messaging.
• AUTOCAD_MCP_NATIVE_PLUGIN=required fails closed when the signed native worker is absent; auto falls back to COM/LISP.
• Prefer the desktop supervisor over MCP-owned startup. AUTOCAD_MCP_AUTOSTART=true remains available for compatibility.
• When attaching to a CAD instance opened by a user, startup/profile/window policy is read-only: it does not rewrite Activity Insights variables or change the window unless AUTOCAD_MCP_APPLY_ACTIVITY_POLICY=true or AUTOCAD_MCP_APPLY_WINDOW_POLICY_TO_EXISTING=true is explicitly set.

Running from WSL

If your MCP client runs in WSL (e.g. Claude Code), launch the server through cmd.exe so it runs as a native Windows process:

{
  "mcpServers": {
    "autocad-mcp": {
      "type": "stdio",
      "command": "cmd.exe",
      "args": ["/d", "/s", "/c", "cd /d C:\\path\\to\\autocad-mcp && .venv\\Scripts\\python.exe -m autocad_mcp"],
      "env": { "AUTOCAD_MCP_BACKEND": "auto" }
    }
  }
}

5. Verify

From your MCP client, call:

system(operation="status")

You should see backend: "file_ipc" if AutoCAD is running, or backend: "ezdxf" for headless mode.

Optional industrial design Skill

skills/industrial-product-design is a client-neutral upstream workflow for briefs, concept gates, product architecture, configurations, motion, camera/render evidence, and honest CAD capability checks. Install or reference that folder in any SKILL.md-compatible client, then use mechanical-drafting-gbt downstream for GB/T manufacturing definition and release.

skills/industrial-product-design-gbt is the comprehensive variant. It adds research-source authority, human-factors evidence, form and surface review, backend routing, local reference-library indexing, and deterministic checks for document identity, 2D/3D interfaces, motion states, render viewsets, and revision-bound handoff manifests. Its personal library manifest is intentionally ignored; generate one locally from the included portable schema.

Tools

drawing — File/drawing management

Operation	Description	File IPC	ezdxf
create	Create and activate a new document, optionally at a managed path	Yes	Yes
context	Return active document ID, path, and monotonic revision	Yes	Yes
activate	Activate a doc_id at an exact expected_revision, then verify active-document readback	Yes	Limited
open	Open an existing drawing	Yes	Yes (DXF)
info	Get entity count and layers	Yes	Yes
save	Save current drawing (to path if given)	Yes	Yes
save_as_dxf	Export as DXF without switching the active DWG	Yes	Yes
plot_pdf	Plot to PDF	Yes	No
render_preview	True PNG with DPI, force-overwrite, dimensions, and SHA-256	Yes	Yes
workspace	Create and report the managed output workspace	Yes	Yes
deliver	Validated DWG/DXF/PDF package with manifest and checksums	Yes	No
audit	Compact structured entity audit with change tracking	Yes	Yes
audit_geometry	Geometry/topology DRC including gaps, dangling endpoints, crossings, tangency, equal radii, and projection checks	Yes	Yes
audit_dxf	Parse an existing DXF into normalized JSON	Yes	Yes
setup_mechanical	Configure mm units, dimensions, sheet metadata, and seven GB/T layers	Yes	Yes
purge	Purge unused objects	Yes	Yes
get_variables	Get system variables by name	Yes	Yes
set_variables	Set a bounded whitelist of units/dimension/linetype variables	Yes	Yes
undo	Undo last operation	Yes	No
redo	Redo last undone operation	Yes	No

entity — Entity CRUD + modification

Create: create_line, create_circle, create_polyline, create_rectangle, create_arc, create_tangent_arc, create_ellipse, create_mtext, create_hatch, create_batch

create_batch accepts up to 500 structured entities in one MCP call. It supports line, circle, polyline, rectangle, arc, ellipse, text, mtext, and hatch records. A hatch can use entity_id: "$last" to reference the preceding entity. The native worker and headless backend provide atomic batches; the compatibility COM/LISP path uses an AutoCAD undo group and returns rollback evidence, but callers must treat an unverified compensation as a hard stop. This is the preferred high-throughput path; it does not enable arbitrary AutoLISP.

For ANSI31, pass angle: 0 to retain the pattern's native 45-degree section angle. scale and hatch layer are also explicit parameters. Every HATCH is read back by handle and checked for type, layer, pattern, angle, and scale; a mismatch is erased and returned as E_POSTCONDITION_MISMATCH.

Read: list, count, get

Modify: copy, move, rotate, scale, mirror, offset*, array, fillet*, chamfer*, trim*, extend*, break*, join*, constrain*, erase

* These native editing operations are File IPC only. trim and extend require explicit entity IDs and pick points so AutoCAD never guesses which side to keep.

constrain reports whether the native command was accepted, but currently returns verified: false because the portable ActiveX API does not expose AutoCAD's associative constraint collection. Treat the constraint as review-required rather than release evidence.

solid - Native AutoCAD 3D solids

create_box, create_cylinder, extrude, revolve, sweep, boolean

The solid tool is available on full AutoCAD through the native ActiveX object model. Box placement uses its center; cylinder placement uses the center of its base. Extrude, revolve, and sweep consume a closed profile handle; boolean accepts union, intersection, or subtract. AutoCAD LT and the ezdxf backend report these operations as unsupported. Edge fillets/chamfers and projected drawing views are not advertised yet because their prompt-driven workflows have not reached the same deterministic standard.

system.status includes an industrial_capabilities matrix. It explicitly separates verified features from unavailable stable edge/face selection, shelling, parametric assemblies, motion sweeps, surface analysis, and offscreen material rendering. Clients must not infer those features from basic solid support.

product - Industrial product features and evidence

create_feature supports rounded_box, recessed_panel, module_reservation, port_cutout_usb_a, port_cutout_usb_c, rotary_layer, annular_gap, and detent_ring_placeholder. The rounded box is a real analytic AutoCAD B-rep assembled from intersecting boxes, edge cylinders, and spherical corners; its radius can be queried from the registered feature definition.

USB cutouts are deliberately gated. A production aperture requires module_status: supplier_controlled|measured, matching authority: supplier_drawing|physical_measurement, do_not_dimension_apertures: false, explicit dimensions, and a target solid. Unverified concepts must use module_reservation, which records that the envelope is not manufacturing authority.

Motion operations are set_motion, interference_sample, and clearance_sweep. They report broad-phase AABB or sampled rotated-AABB evidence and always state exact_brep_interference: false; release work still requires an exact native continuous sweep.

render_view accepts front, right, top, bottom, iso, rotated_iso, section, and exploded. Section/exploded views require caller-prepared geometry. The result includes fixed camera data, PNG hash, content bounds, non-background ratio, clipping, framing status, and optional pixel difference. Pass an allow-listed visual_style to request an AutoCAD display style; the response separately reports style readback, restoration verification, and material_render_verified (currently false for the compatibility plot path). This remains a native AutoCAD plot, not an offscreen material renderer.

set_review and review_summary keep appearance_review, ergonomics_review, adapter_clearance_review, cable_management_review, stability_review, and mains_rotation_safety_review separate from geometry/STEP validity. Each is PASS, FAIL, or NOT_EVALUATED; PASS requires evidence.

General fillet_edges and chamfer_edges reject volatile native edge indices with E_STABLE_FEATURE_SELECTION_UNAVAILABLE. Use analytic features now. A future OpenCascade/FreeCAD plugin may provide selector-based general edge operations without weakening the AutoCAD document and transaction contract.

On the COM/LISP compatibility backend, destructive product replacements (recessed_panel, port_cutout_usb_a, and port_cutout_usb_c) fail closed with E_COMPAT_FEATURE_TRANSACTION_UNAVAILABLE because ActiveX cannot prove an atomic replacement. Use the signed native worker; the unsafe compatibility fallback requires an explicit AUTOCAD_MCP_ALLOW_UNVERIFIED_COMPAT_CUTOUTS=true and is unsuitable for release work.

The 3D protocol borrows proven patterns from build123d, build123d-mcp, FreeCAD MCP, and Open CASCADE fillet/chamfer APIs: explicit parameter sources, semantic/property selectors, measure-render-validate loops, and honest kernel capability boundaries.

layer — Layer management

list, create, set_current, set_properties, freeze, thaw, lock, unlock

block — Block operations

Operation	File IPC	ezdxf
list	Yes	Yes
insert	Yes	Yes
insert_with_attributes	Yes	Yes
get_attributes	Yes	Yes
update_attribute	Yes	Yes
define	No	Yes

annotation — Text, dimensions, leaders

create_text, create_dimension_linear, create_dimension_aligned, create_dimension_angular, create_dimension_radius, create_leader

pid — P&ID operations (CTO symbol library)

setup_layers, insert_symbol, list_symbols, draw_process_line, connect_equipment, add_flow_arrow, add_equipment_tag, add_line_number, insert_valve, insert_instrument, insert_pump, insert_tank

P&ID symbol insertion requires the CAD Tools Online (CTO) P&ID Symbol Library installed at C:\PIDv4-CTO\. The ezdxf backend has built-in CTO library support. For the File IPC backend, some P&ID operations require additional LISP helpers — see the P&ID section in the wiki for setup details.

view — Viewport and diagnostic capture

Operation	Description
zoom_extents	Zoom to show all entities
zoom_window	Zoom to a specified window
set_visual_style	Apply an allowlisted built-in style (Conceptual, Realistic, Shaded, etc.) with optional verified entity colors; requires doc_id and expected_revision
get_screenshot	Diagnostic-only capture; returns a managed PNG path, dimensions, and SHA-256 by default. Raw image content requires data.include_image=true plus AUTOCAD_MCP_ALLOW_INLINE_IMAGES=true.

Normal validation is data-first: use drawing.audit after edits and drawing.render_preview at milestones. get_screenshot remains available only for diagnosing AutoCAD UI state. The MCP serializes AutoCAD calls and caps response/call bursts so a parallel screenshot loop cannot exhaust the client context.

transaction - Document-scoped transactions

context, create, execute, plus compatibility begin, commit, rollback

For the native path, call context, then send one strict execute request with a stable idempotency_key. The plugin validates the active document and revision, opens one database transaction, rejects missing layers before creation, and commits all operations or none. A document mismatch returns E_DOCUMENT_ID_MISMATCH; stale revision data returns E_DOCUMENT_REVISION_MISMATCH. Successful idempotent requests can be replayed; failed requests are not cached and remain retryable.

{
  "operation": "execute",
  "doc_id": "acad-...",
  "expected_revision": 12,
  "idempotency_key": "gearbox-stage-01",
  "data": {
    "session_id": "native-...",
    "operations": [
      {
        "type": "solid.box",
        "resultId": "body",
        "featureId": "gearbox-body",
        "center": [0, 0, 20],
        "length": 120,
        "width": 80,
        "height": 40,
        "layer": "0"
      },
      {
        "type": "solid.cylinder",
        "resultId": "bore",
        "baseCenter": [0, 0, -1],
        "radius": 12,
        "height": 42,
        "layer": "0"
      },
      {
        "type": "solid.boolean",
        "resultId": "finished",
        "primaryRef": "body",
        "toolRef": "bore",
        "operation": "subtract",
        "layer": "0"
      }
    ]
  }
}

The older begin/commit/rollback operations remain for AutoCAD LT and compatibility workflows. They use undo marks and do not replace the native database transaction when the plugin is available.

Layer names are preconditions. Creating geometry on an absent layer returns E_LAYER_NOT_FOUND before mutation instead of silently falling back to layer 0.

Data-first validation

edit entities -> drawing.audit -> native render_preview -> audit_dxf for final delivery

drawing.audit returns entity counts by type and layer, drawing bounds, units, a handle-independent geometry digest, geometry DRC, an endpoint topology graph, limited normalized entity geometry, and added/modified/removed handles since the previous audit. In addition to degenerate geometry, rules can check connection gaps, dangling endpoints, interior crossings, explicit tangent pairs, equal-radius groups, and cross-view projection alignment. limit is clamped to 500 so large drawings do not flood model context.

drawing.render_preview always returns a real PNG. Full AutoCAD writes it through the native PNG plot device without capturing the desktop or opening a viewer. The result includes DPI, pixel size, orientation correction, SHA-256, and the source geometry digest. Add visual_style to request a controlled display style; the response reports actual style restoration and whether material rendering was independently verified. drawing.plot_pdf remains the release-quality vector output.

Industrial delivery jobs

drawing.deliver turns the active drawing into a traceable job rather than treating a successful script as a finished drawing. It creates an isolated folder under jobs, records the request under specs, audits the source, applies geometry gates, saves DWG/DXF/PDF, audits the exported DXF, compares type/layer counts, bounds, units and geometry digests, writes reports/validation.json, and records artifact sizes and SHA-256 hashes.

{
  "operation": "deliver",
  "data": {
    "name": "gearbox-output-shaft",
    "metadata": {"drawing_number": "GB-OS-001", "revision": "A"},
    "plot": {
      "paper": "A3",
      "orientation": "landscape",
      "plot_style": "monochrome.ctb",
      "scale_mode": "fixed",
      "scale": "1:1",
      "center": true
    },
    "validation": {
      "min_entities": 20,
      "required_layers": ["OUTLINE", "CENTER", "DIM"],
      "required_types": ["LINE", "CIRCLE", "DIMENSION"],
      "require_geometry_clean": true,
      "geometry_tolerance": 0.000001
    }
  }
}

The job contains specs/request.json, manifest.json, editable DWG and DXF files, a native PDF, audits/drawing-audit.json, and reports/validation.json. Failed validation or export leaves a failed manifest with step-level diagnostics.

Industrial automation roadmap

• v3.6 reliability (compatibility foundation): self-healing startup, dispatcher version handshake, machine-readable MCP failures, controlled variables, geometry DRC, DXF units/digests, and enforced plot configuration; live AutoCAD profile repairs remain opt-in.
• v3.7 geometry control (compatibility foundation): topology DRC, bounded batches, safe trim/extend/break/join/constraints, native 3D solids, non-switching DXF export, and verified file/framing checks; COM rollback remains explicitly bounded.
• v3.8 entity truth (implemented with gates): immutable entity contracts, semantic topology, no-focus desktop behavior, and postcondition readback; unresolved context failures are terminal and require reconciliation.
• v3.9 document/output reliability (implemented with gates): document identity, transactions, crash classification, offline audits, atomic outputs, plot verification, and viewer suppression; exact guarantees require the native worker.
• v3.10 product 3D foundation (concept/engineering candidate): analytic rounded products, controlled module envelopes, broad-phase motion screening, fixed-camera evidence, semantic DRC, and independent product reviews; exact assemblies, material rendering, and continuous sweeps remain unsupported.
• v4.0 hybrid CAD: FreeCAD CLI/MCP as the parameterized 3D and STEP executor, AutoCAD as the visible DWG/2D drafting and release executor, with shared specs and acceptance reports.

system — Server management

status, ensure_ready, health, get_backend, runtime, init, recover, execute_lisp

status is observational and does not start AutoCAD. ensure_ready performs the full discovery/start/document/dispatcher/version/ping sequence and reports the detected AutoCAD product without assuming AutoCAD LT.

Tool failures use MCP isError=true and a stable structure containing code, message, recoverable, and recommended_action.

recover cancels stale AutoCAD command-line state and removes abandoned IPC files without calling the potentially blocked dispatcher. Arbitrary AutoLISP remains disabled unless AUTOCAD_MCP_ALLOW_ARBITRARY_LISP=true is explicitly configured.

execute_lisp is an explicit opt-in escape hatch for trusted local use. Normal automation should use the structured tools and create_batch.

Architecture

MCP Client (Codex / Claude Code / Claude Desktop / Cursor)
    │  stdio (JSON-RPC)
    ▼
Python MCP Server (autocad_mcp)
    │
    ├── File IPC Backend ──► C:/temp/*.json ──► mcp_dispatch.lsp
    │   ├── Full AutoCAD: COM ActiveDocument.SendCommand
    │   └── AutoCAD LT: PostMessageW(WM_CHAR) to MDIClient
    │
    └── ezdxf Backend ──► in-memory DXF (headless, no AutoCAD needed)

The File IPC backend sends (c:mcp-dispatch) to the active drawing. Full AutoCAD uses COM ActiveDocument.SendCommand; AutoCAD LT falls back to PostMessageW(WM_CHAR). Both paths avoid taking over normal mouse input.

Environment Variables

Variable	Default	Description
AUTOCAD_MCP_BACKEND	auto	Backend selection: auto, file_ipc, ezdxf
AUTOCAD_MCP_NATIVE_PLUGIN	auto	Native worker policy: auto, required, or off
AUTOCAD_MCP_NATIVE_WORKER_DIR	%LOCALAPPDATA%/AutoCAD-MCP/workers	Native worker descriptor directory
AUTOCAD_MCP_PLUGIN_TOKEN	empty	Optional shared token required by the current-user native pipe
AUTOCAD_MCP_SUPERVISOR_DIR	%LOCALAPPDATA%/AutoCAD-MCP/supervisor	Desktop supervisor state, stop request, and UTF-8 BOM log directory
AUTOCAD_MCP_IPC_DIR	C:/temp	Directory for IPC command/result JSON files (must match on both Python and LISP sides)
AUTOCAD_MCP_IPC_TIMEOUT	10.0	IPC command timeout in seconds (1-300)
AUTOCAD_MCP_DOCUMENT_TIMEOUT	30.0	Seconds to wait for COM registration and an active document after the window appears (5-120)
AUTOCAD_MCP_ONLY_TEXT	true	Disable automatic screenshot attachments; direct diagnostic capture remains available
AUTOCAD_MCP_ALLOW_INLINE_IMAGES	false	Explicitly allow raw screenshot image content in MCP responses; leave disabled to return path/hash metadata
AUTOCAD_MCP_MAX_INLINE_IMAGE_BYTES	262144	Maximum PNG bytes allowed in an explicitly requested inline image
AUTOCAD_MCP_MAX_RESPONSE_BYTES	524288	Hard response ceiling; oversized lists are replaced by a hash/count evidence envelope
AUTOCAD_MCP_TRANSPORT_WINDOW_BUDGET (alias AUTOCAD_MCP_MAX_CALLS_PER_WINDOW)	120	Sliding-window MCP admission budget; prefer the namespaced variable, while AutoCAD calls remain serialized
AUTOCAD_MCP_TRANSPORT_WINDOW_SECONDS (alias AUTOCAD_MCP_CALL_WINDOW_SECONDS)	60	Sliding-window duration for the MCP admission budget
AUTOCAD_MCP_TRANSPORT_MAX_QUEUE	32	Maximum queued calls waiting for the single AutoCAD lane
AUTOCAD_MCP_TRANSPORT_QUEUE_TIMEOUT (alias AUTOCAD_MCP_REQUEST_QUEUE_TIMEOUT)	30	Maximum time a concurrent request waits for the single AutoCAD queue
AUTOCAD_MCP_AUTOSTART	false	Start AutoCAD automatically when File IPC is requested and no AutoCAD window exists
AUTOCAD_MCP_ACAD_PROFILE	empty	Optional existing profile name or exported .arg path passed through /p; never changes the user's current profile
AUTOCAD_MCP_PROFILE_MODE	existing	existing/explicit; isolated or required fails closed unless an explicit profile/ARG is supplied
AUTOCAD_MCP_ACAD_EXTRA_ARGS	empty	Additional shell-free AutoCAD startup switches, parsed as an argument list
AUTOCAD_MCP_STARTUP_STABILITY_READS	3	Consecutive identical non-fatal HWND observations required before readiness (1-10)
AUTOCAD_MCP_STARTUP_SETTLE	0.75	Seconds to recheck the fatal-dialog state after the stable HWND gate
AUTOCAD_MCP_AUTOSTART_FAILURE_COOLDOWN	900	Seconds to refuse an identical failed autostart signature, preventing retry loops
AUTOCAD_MCP_AUTOSTART_FORCE_RETRY	false	One-shot escape hatch after the profile or installation has been repaired
AUTOCAD_MCP_START_MINIMIZED	true	Launch with a minimize hint so AutoCAD does not jump in front of other work
AUTOCAD_MCP_CER_FILE	empty	Optional explicit Autodesk CER rawdata-t1.pb/rawdata-t2.pb path for offline crash evidence
AUTOCAD_MCP_VISIBLE	true	Keep AutoCAD as a visible desktop application rather than a hidden automation session
AUTOCAD_MCP_WINDOW_MODE	quiet_minimized	preserve for an existing user window, quiet_minimized (backend-owned taskbar window), visible, or explicit recording; legacy aliases remain accepted
AUTOCAD_MCP_ACTIVATE_ON_DRAW	false	Allow per-command activation only when AUTOCAD_MCP_WINDOW_MODE=foreground
AUTOCAD_MCP_APPLY_ACTIVITY_POLICY	false	Permit Activity Insights variable writes after a backend-owned launch
AUTOCAD_MCP_APPLY_WINDOW_POLICY_TO_EXISTING	false	Permit implicit visibility/minimize changes to a user-owned AutoCAD window
AUTOCAD_MCP_COM_MUTEX_TIMEOUT	5	Seconds to wait for another MCP process to release the per-user COM mutex
AUTOCAD_MCP_AUTO_FIT	true	Automatically center and fit drawing extents after geometry changes
AUTOCAD_MCP_OUTPUT_ROOT	~/Documents/AutoCAD-MCP	Unified output root; this workstation should set D:/Codex/AutoCAD-MCP
AUTOCAD_MCP_LOG_PATH	<output-root>/logs/autocad-mcp.log	BOM-prefixed UTF-8 diagnostic log readable by Windows PowerShell
AUTOCAD_MCP_ALLOW_EXTERNAL_OUTPUTS	false	Permit writes outside the managed output root; disabled by default
AUTOCAD_MCP_ACAD_EXE	empty	Full path to acad.exe used by automatic startup
AUTOCAD_MCP_ACAD_SCRIPT	empty	Optional AutoCAD .scr file passed with /b during startup
AUTOCAD_MCP_ACAD_STARTUP_TIMEOUT	75	Seconds to wait for the AutoCAD main window, clamped to 5-180
AUTOCAD_MCP_LISP_PATH	empty	Dispatcher path loaded for the current AutoCAD session only
AUTOCAD_MCP_CAMPAIGN_OPERATION_TIMEOUT	120	Hard timeout for one live-CAD regression operation (5-300)
AUTOCAD_MCP_CAMPAIGN_TIMEOUT	900	Hard timeout for the complete live-CAD regression campaign (30-3600)

The managed regression runners are deliberately fail-closed. A timed-out COM call quarantines its STA worker (E_COM_STA_TIMEOUT) and refuses follow-up requests until the MCP worker is restarted; a timed-out pytest slice attempts to terminate its complete process tree and records any cleanup limitation. This prevents a stalled AutoCAD/COM process from holding an MCP client turn indefinitely.

mcp_dispatch.lsp reads AUTOCAD_MCP_IPC_DIR from the AutoCAD process environment and falls back to C:/temp.

drawing.audit_dxf is an offline operation and does not start AutoCAD, require an active document, or ping the dispatcher. drawing.plot_pdf defaults to A3, landscape, and FIT; the result includes requested settings, actual document/output paths, PDF mediabox dimensions, detected paper/orientation, and field-level differences.

Development

uv sync
uv run pytest tests/ -v

AutoCAD LT AutoLISP Compatibility

AutoLISP was added to AutoCAD LT in the 2024 release (Windows only). AutoCAD LT for Mac does not support AutoLISP.

Supported (LT 2024+ Windows)	Not Supported
.lsp / .fas / .vlx / .dcl	VLIDE (Visual LISP IDE)
All vl-* utility functions	vlax-* (ActiveX/COM)
File I/O (open, read-line, etc.)	Express Tools
Entity access (entget, entmod, etc.)	3D operations
Selection sets	AutoLISP on Mac

The mcp_dispatch.lsp dispatcher is fully compatible with LT 2024+.

What's New in v4.0

• Native transaction worker - current-user named pipes connect standard MCP clients to a .NET worker using DocumentLock, database transactions, database-event revisions, and stable XData feature IDs.
• Fail-closed document fencing - native writes require session, document ID, expected revision, and a stable idempotency key; active-document mismatch or stale revision prevents all mutation.
• Durable replay safety - Python journals accepted/committed/failed jobs; the plugin caches only committed successes and hashes semantic requests without transport IDs or credentials.
• Desktop supervisor - a user-owned process manages PID/HWND/profile health while keeping AutoCAD taskbar-visible, minimized, focus-safe, and independent of Codex, Claude Code, or another client's sandbox.
• Signed bundle flow - source builds can Authenticode-sign, verify, and install the AutoCAD bundle without disabling SECURELOAD.
• Managed test cleanup - CAD artifacts are deleted only inside a confirmed job directory while hashes, manifests, audits, reports, and logs remain.

v3.10

• Analytic native rounded products - rounded_box creates real radius geometry without relying on volatile native edge indices.
• Controlled module authority - concept, supplier-controlled, and measured modules carry explicit dimension authority; unverified USB apertures are rejected.
• Motion evidence - rotation axes, limits, static AABB screening, and sampled rotated-AABB clearance sweeps are machine-readable and explicitly non-exact.
• Fixed-camera review packets - standard views return camera parameters, PNG hashes, content bounds, margins, clipping, framing status, and optional pixel differences.
• Semantic DRC - component, design role, view, line class, intentional open end, permitted crossing, and source authority keep overlays out of geometry failures.
• Independent product review - appearance, ergonomics, adapter clearance, cable management, stability, and mains/rotation safety cannot inherit a PASS from valid geometry.
• Honest edge capability - general 3D fillet/chamfer calls return E_STABLE_FEATURE_SELECTION_UNAVAILABLE; analytic features remain measurable and safe.

v3.9

• Document identity and optimistic revisions - create/open/activate/context responses carry document ID, requested/active paths, and monotonic revision; all modifications reject wrong or stale contexts.
• Public transactions - explicit begin/commit/rollback joins atomic batch rollback and missing-layer preconditions.
• Crash and system error classification - fatal AutoCAD state, COM failures, file paths, system calls, errno/winerror, and recovery actions use structured error envelopes.
• Read-only delivery copies - DWG packaging uses Wblock and verifies the active source document and path did not change.
• Offline DXF audits - DXF parsing does not start AutoCAD or require a dispatcher or active document.
• Atomic outputs - PDF and PNG publish through validated temporary files; locked destinations return E_OUTPUT_LOCKED without half-written artifacts.
• Verified paper and orientation - A3 landscape FIT is the PDF default, mediabox settings are read back, and device-rotated PNG output is normalized.
• No viewer focus theft - a per-output window guard hides and closes only the exact temporary PDF opened by an external viewer, restores the last non-AutoCAD user window, and records suppression evidence.
• Cold-start stability gate - AutoCAD must return the same active document through consecutive COM reads; dispatcher loading is retried within a fixed bound before readiness is reported.
• Honest industrial capability reporting - status exposes verified features and names advanced 3D, assembly, analysis, selection, and rendering functions that remain unsupported.

v3.8

• Immutable entity contracts - strict requests are read back by handle with requested, actual, and diff; mismatches are deleted and fail the atomic batch.
• Semantic topology - component ownership, line class, and intentional open ends feed stricter dangling-endpoint and crossing audits.
• No-focus desktop behavior - AutoCAD remains user-visible in the taskbar but minimized by default, drawing calls do not steal focus, and PDF/PNG viewers are never launched.

v3.7

• Topology-aware DRC - audits expose endpoint connectivity and configurable checks for near misses, dangling endpoints, non-endpoint crossings, tangency, equal-radius groups, and projection alignment.
• Atomic batches - create_batch opens an AutoCAD undo transaction by default and rolls back the whole batch on failure.
• Controlled 2D repair - explicit trim, extend, break, join, geometric constraints, and mathematically solved tangent arcs replace blind coordinate patching.
• Native 3D solids - full AutoCAD supports boxes, cylinders, extrusions, revolutions, sweeps, and boolean operations through a dedicated safe tool.
• True PNG previews - native AutoCAD plotting is rasterized to a force-overwritable white-background PNG with DPI, dimensions, hashes, and no desktop capture.
• Non-switching DXF export - save_as_dxf uses AutoCAD's export API and verifies that the active DWG remains unchanged.
• Richer entity data - arc endpoints, polyline bulges, MText width/attachment, block attributes, bounds, length, area, and object ownership are returned when available.

v3.6

• Self-healing readiness - system.ensure_ready discovers or starts AutoCAD, ensures an active document, loads the configured or bundled dispatcher, verifies its version, and pings IPC.
• Structured MCP errors - failures are marked isError=true and use stable error codes such as E_DISPATCHER_NOT_LOADED, E_IPC_TIMEOUT, and E_OUTPUT_PATH_REJECTED.
• Safe variable updates - drawing.set_variables exposes a validated whitelist; setup_mechanical now applies millimeter and dimension defaults in addition to layers.
• Geometry DRC - source and exported DXF audits detect zero/short segments, duplicate vertices/endpoints/entities, and polyline self-intersections.
• Stronger DXF evidence - audits report $INSUNITS and a handle-independent geometry digest; delivery compares types, layers, bounds, units, digest, and DRC.
• Enforced plotting - plot_pdf and deliver apply and record paper, orientation, plot style, fixed/fit scale, centering, device, media, and paper units.

v3.5

• Unified managed workspace - output paths default to the portable ~/Documents/AutoCAD-MCP; each client can override it with AUTOCAD_MCP_OUTPUT_ROOT (for example D:/CAD-Automation).
• Output containment - save/export paths outside the managed root are redirected unless external outputs are explicitly enabled.
• Validated delivery jobs - drawing.deliver produces DWG, DXF, PDF, request/audit JSON, a step manifest, validation results, file sizes, and SHA-256 checksums.
• Quality gates - delivery can require minimum/maximum entity counts plus required layers and entity types, and rejects DXF exports whose entity count differs from the source.

v3.4

• Prompt-free layer management - common center and hidden linetypes are created or loaded without opening an interactive linetype prompt.
• Mechanical drafting profile - drawing.setup_mechanical creates OUTLINE, THIN, CENTER, HIDDEN, HATCH, DIM, and TEXT with monochrome GB/T lineweights.
• Structured batch creation - up to 500 whitelisted entities can be submitted in one MCP call without enabling arbitrary AutoLISP.
• Portable Chinese text - File IPC converts non-ASCII annotation text to AutoCAD \\U+XXXX escapes.
• Reliable hatching - pattern angle and scale are explicit; ANSI31 defaults to an added angle of zero.
• Out-of-band recovery - system.recover cancels stuck commands and cleans IPC state without waiting for the dispatcher.
• Native save path - full AutoCAD saves DWG/DXF through COM first and uses the AutoLISP command path only as a fallback.
• Automation-session discovery - hidden AutoCAD instances can be found through their COM window handle when no visible main window is available.
• TEXT audit fix - final DXF audits read TEXT and MTEXT heights through their correct entity-specific attributes.
• Live visible drawing - AutoCAD is restored before drawing by default; optional foreground activation and view.show_window make automation observable in real time.
• Startup busy retry - transient COM call rejection during AutoCAD startup is retried briefly before the Win32 fallback is used.
• Idle-state synchronization - each IPC request waits for AutoCAD to finish unwinding the previous dispatcher before sending the next command.
• Verified entity creation - rectangles, hatches, and dimensions report an error when no new CAD entity was actually created.
• Native COM dimensions - full AutoCAD creates linear, aligned, angular, and radial dimensions directly through ActiveX, with AutoLISP retained as the LT fallback.
• Automatic centered view - geometry changes automatically fit all extents into the viewport; structured batches fit once after completion, and view.fit_drawing can trigger it manually.

v3.3

• Structured drawing audits - compact counts, layers, bounds, normalized geometry, and change fingerprints.
• Native preview rendering - full AutoCAD plots PDF through PlotToFile; ezdxf writes deterministic PNG.
• DXF mathematical audit - parses existing DXF files into bounded normalized JSON instead of returning raw DXF text.
• Data-first defaults - automatic screenshot feedback is disabled by default; window capture is diagnostic only.
• Richer AutoLISP entity details - arcs, polylines, text, blocks, and dimensions report useful geometry.

v3.2

• Full AutoCAD COM transport - sends command expressions through ActiveDocument.SendCommand.
• Process-based window detection - recognizes localized titles and the AutoCAD Start page by verifying acad.exe.
• Optional AutoCAD startup - launches a configured acad.exe and waits for its window.
• Session-scoped dispatcher loading - loads a configured LISP dispatcher without changing persistent trust paths.

v3.1

• execute_lisp — Run arbitrary AutoLISP code via temp file pattern. Turns the server from a fixed command set into an extensible automation platform.
• Undo / Redo — Single-step undo and redo via drawing tool.
• Drawing open — Open existing .dwg files programmatically (FILEDIA suppressed).
• Drawing create — Now resets current drawing (erase all + purge) instead of _.NEW, preserving the LISP dispatcher namespace.
• Drawing save with path — save with a path parameter uses SAVEAS; without path uses QSAVE.
• get_variables fix — Respects the names parameter; returns requested variables with proper type handling.
• Polyline/leader fix — Point arrays properly encoded via semicolon-delimited format.
• ESC prefix — Sends 2x ESC before each dispatch to cancel stale pending commands from prior timeouts.
• UTF-8/cp1252 fallback — Handles non-ASCII characters in LISP result files (AutoCAD writes Windows-1252).
• Configurable IPC timeout — AUTOCAD_MCP_IPC_TIMEOUT env var (1–300 seconds, default 10).
• Thread-safe backend init — asyncio.Lock prevents parallel initialization races.

License

MIT