ipt-mcp

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ipt-mcp is an open-source (Apache-2.0) Model Context Protocol gateway that lets Claude Code — and any MCP-capable client — drive Autodesk Inventor 2022-2027 locally.

The agent speaks MCP over stdio. The server speaks NDJSON over a local authenticated transport (TCP or Named Pipe) to a per-version in-process Inventor add-in. The add-in marshals every command onto Inventor's STA thread and talks to the Inventor API.

Your model stays on your machine.

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What ipt-mcp Is

Two processes, one local pipe:

• Bimwright.Ipt.Server.exe — a .NET 8 MCP stdio server launched by Claude Code, Cursor, Cline, Codex, or another stdio MCP client. It has no Inventor reference; it only compiles the API-agnostic contract files, so it builds and runs on any machine with the .NET 8 SDK.
• Bimwright.Ipt.Plugin.InvNN.dll — an ApplicationAddInServer add-in that loads inside Inventor.exe, runs a TCP or Named-Pipe listener, and executes commands on Inventor's main UI (STA) thread. One thin shell per Inventor year, all compiled from the same src/shared/** source glob.

Unlike Revit, Inventor has no ExternalEvent equivalent. The add-in marshals work onto the STA thread through a hidden message-only WinForms control (InventorStaDispatcher). See ARCHITECTURE.md for the full design.

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Supported Inventor Versions

Inventor	Target framework	Transport	Notes
2022	net48 (.NET Framework 4.8)	TCP	references System.Windows.Forms directly
2023	net48 (.NET Framework 4.8)	TCP
2024	net48 (.NET Framework 4.8)	TCP
2025	net8.0-windows7.0	Named Pipe	UseWindowsForms, EnableDynamicLoading
2026	net8.0-windows7.0	Named Pipe
2027	net10.0-windows7.0	Named Pipe	needs the .NET 10 SDK; honors UseInventorAssemblyContext

• The MCP server is one process, unaffected by the Inventor version — it just forwards JSON envelopes.
• TCP for 2022-2024 (net48 add-ins); Named Pipe for 2025-2027 — Named Pipe avoids the loopback-firewall prompt on modern Windows.
• Inventor moved desktop add-in development off .NET Framework starting in 2025: .NET 8 for 2025/2026, .NET 10 for 2027. (.NET 8 add-ins remain binary-compatible on 2027, but net10 is the native target.)
• Use 4-digit calendar years (2022..2027) everywhere — never legacy version codes.

Status: verified. Phases 1-3 are complete and green (46 MCP tools; server + tests build with no Inventor installed), and the Inventor-API handlers have been exercised against a live Inventor session. As always, test against your own templates before trusting it on production models.

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Install / Wire an MCP Client

The server is a plain stdio MCP process. Point your client at the built Bimwright.Ipt.Server.exe (or dotnet run it), then load the add-in inside Inventor.

A typical .mcp.json (or equivalent client config) entry:

{
  "mcpServers": {
    "ipt-mcp": {
      "command": "D:\\path\\to\\src\\server\\bin\\Debug\\net8.0\\Bimwright.Ipt.Server.exe",
      "args": []
    }
  }
}

Add-in discovery is automatic: each running Inventor add-in writes a per-instance descriptor under %LOCALAPPDATA%\Bimwright\ipt-mcp\inventor-<year>-<pid>.json. The server scans these, deletes dead/stale descriptors best-effort, and connects. MCP target-list tools redact the descriptor auth_token. When more than one Inventor may be open, call inventor_list_available_targets then inventor_switch_target.

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Build & Develop

Autodesk Inventor binaries and the Inventor SDK are not redistributed in this repo (see Not Redistributed). Building the server and tests needs only the .NET 8 SDK; building a per-version add-in needs the matching SDK plus the Inventor interop reference assembly.

# Server + tests (server-only; NO Inventor required — works on any machine with the .NET 8 SDK):
dotnet build src/IptMcp.sln -c Debug
dotnet test  tests/Bimwright.Ipt.Tests -c Debug

# Add-in project SHAPE check without Inventor installed:
dotnet build src/plugin-inv24 -c Debug /p:SkipInventorReferenceCheck=true
dotnet build src/plugin-inv27 -c Debug /p:SkipInventorReferenceCheck=true   # needs the .NET 10 SDK

# Real add-in compile (only on a box with Inventor + the matching SDK): drop SkipInventorReferenceCheck.
# Pass /p:InventorInteropDir=... if the interop is not at the default path.

• The server explicit-includes only shared/Contracts/* + shared/Security/* (+ ToolBaker), so it compiles with no Inventor SDK present.
• Each add-in uses <Compile Include="..\shared\**\*.cs" /> to pull in everything, including the API-touching Infrastructure/Plugin/Handlers.
• The default interop hint path is C:\Program Files\Common Files\Autodesk Shared\Extensions <year>\Framework\Interop\Autodesk.Inventor.Interop.dll.
• Building add-in 2027 needs the .NET 10 SDK installed.
• Close Inventor before deploying add-in DLLs it would otherwise lock.

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Tool Surface

The full surface is 46 tools when all platform toolsets are enabled. Every MCP-facing name is prefixed inventor_. Tools are grouped into toolset classes; --toolsets sketch,feature and --read-only gate which ones register so weak models never see disabled tools.

Default-on toolsets: meta, query, document, parameters, properties, sketch, feature, export, toolbaker, toolbaker_write. Off by default: code (the send_code escape hatch — opt-in only).

All length inputs are in mm, angles in degrees; the add-in converts to Inventor's internal centimetres/radians.

meta (3) — server-side target tools, never round-trip to the add-in; stay exposed under --read-only

Tool	Description
inventor_list_available_targets	List detected live Inventor add-in targets (year, pid, transport, active document).
inventor_get_current_target	Report the server's currently selected target, or NO_TARGET if none is live.
inventor_switch_target	Select the active target by descriptor id, Inventor year, process id, or pipe/session name. Server-side only.

query (3) — read-only document/health probes

Tool	Description
inventor_health	Probe the active add-in: inventor_year, process_id, whether a document is open, active document type.
inventor_list_open_documents	List all open documents: title, path, type, and which is active.
inventor_get_document_info	Get the active document's title, full path, and document type.

document (7) — document lifecycle (write)

Tool	Description
inventor_new_part	Create a new part document (.ipt); optional template path.
inventor_new_assembly	Create a new assembly document (.iam); optional template path.
inventor_open_document	Open an existing document from a full path and make it active.
inventor_save_document	Save the active document, or Save-As to a given path.
inventor_close_document	Close the active document; save=true saves first.
inventor_set_units	Set the active document's length unit (mm, cm, m, in, ft).
inventor_set_material	Assign a material to the active part by name.

parameters (4) — model & user parameters (write)

Tool	Description
inventor_list_parameters	List parameters (model + user): name, expression, value, unit, kind.
inventor_get_parameter	Get one parameter by name: expression, value, unit.
inventor_set_parameter	Set an existing parameter's expression/value, then update the document.
inventor_create_parameter	Create a new user parameter (name, expression, unit).

properties (3) — iProperties & mass properties (write)

Tool	Description
inventor_get_iproperty	Get an iProperty value by property-set and property name.
inventor_set_iproperty	Set an iProperty value.
inventor_get_mass_properties	Mass (g), volume (mm³), surface area (mm²), centre of mass, bounding box.

sketch (9) — 2D sketch geometry & constraints (write)

Tool	Description
inventor_create_sketch	Create a 2D sketch on a plane (XY/XZ/YZ or a face/work-plane reference).
inventor_project_geometry	Project model edges/vertices (by edge ids) into the active sketch.
inventor_draw_line	Draw a sketch line from (x1,y1) to (x2,y2).
inventor_draw_circle	Draw a sketch circle from centre + radius.
inventor_draw_rectangle	Draw a two-point sketch rectangle.
inventor_draw_arc	Draw a sketch arc (centre, radius, start/end angle).
inventor_add_sketch_dimension	Add a driving dimension constraint to a sketch entity.
inventor_add_sketch_constraint	Add a geometric constraint (coincident, parallel, tangent, …).
inventor_close_sketch	Finish editing a sketch (exit sketch edit mode).

feature (6) — solid & work features (write)

Tool	Description
inventor_extrude	Extrude a named sketch (distance, join/cut/intersect, direction).
inventor_revolve	Revolve a named sketch about an axis (angle, operation).
inventor_fillet	Add a constant-radius edge fillet over model edges.
inventor_chamfer	Add an equal-distance edge chamfer over model edges.
inventor_create_work_plane	Create a work plane (offset, three_points, or tangent).
inventor_create_work_axis	Create a work axis (two_points, edge, plane_intersection, normal_to_face_through_point).

export (4) — view capture & geometry export (write)

Tool	Description
inventor_capture_view	Capture the active view as a bounded base64 PNG (no file written).
inventor_export_step	Export the active part/assembly to STEP (.stp/.step).
inventor_export_stl	Export the active part/assembly to STL (.stl).
inventor_export_dxf	Export a 2D DXF; must declare source (sketch or flat_pattern).

Export paths must be absolute and under an allowed output root (user profile or temp).

code (1) — opt-in escape hatch (OFF by default)

Tool	Description
inventor_send_code	Dangerous, opt-in only. Execute a C# snippet in-process against Inventor.Application. Disabled unless both server and add-in opt in (else SEND_CODE_DISABLED); banned APIs (file/process/network/environment) are rejected.

toolbaker (3, read-only) — operate purely on the server-side bake database

Tool	Description
inventor_list_baked_tools	List all verified, compiled, registered baked tools.
inventor_list_bake_suggestions	List active ToolBaker suggestions from recurrent workflows.
inventor_create_bake_issue_draft	Create a GitHub issue draft for a suggestion (without submitting).

toolbaker_write (3, write) — run baked tools and manage the suggestion lifecycle

Tool	Description
inventor_run_baked_tool	Execute a registered baked tool by name with JSON parameters.
inventor_accept_bake_suggestion	Accept a suggestion: validate + compile + apply + persist as a baked tool.
inventor_dismiss_bake_suggestion	Dismiss or snooze an active suggestion.

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Safety

Short version: your model stays on your machine, and write/dangerous tools are gated.

• Read-only mode. --read-only (or BIMWRIGHT_INVENTOR_READ_ONLY=1) removes every write-capable toolset (document, parameters, properties, sketch, feature, export, code, toolbaker_write) but keeps meta + query + read-only toolbaker, and keeps inventor_switch_target exposed. The server sends read-only mode in each command envelope; the add-in also honors BIMWRIGHT_INVENTOR_PLUGIN_READ_ONLY=1 / BIMWRIGHT_INVENTOR_READ_ONLY=1. A write command under enforced read-only returns READ_ONLY.
• send_code two-sided opt-in. inventor_send_code is disabled by default. It is exposed only when both gates are set: the server with --enable-send-code (or BIMWRIGHT_INVENTOR_ENABLE_SEND_CODE=1) and the add-in process with BIMWRIGHT_INVENTOR_PLUGIN_ENABLE_SEND_CODE=1. Otherwise the dispatcher returns SEND_CODE_DISABLED. Banned APIs (file/process/network/environment) are rejected.
• Local, authenticated transport. TCP binds loopback; Named Pipe is local-machine scoped. Each per-session descriptor carries a random auth token, but MCP meta tools never return it.
• Sanitized errors. Error messages returned to the model are sanitized to avoid leaking absolute paths/secrets.

ToolBaker turns repeated local workflows into personal, verified tools: suggestions surface through inventor_list_bake_suggestions, you explicitly accept one with inventor_accept_bake_suggestion (validate → compile → apply → persist), and accepted tools become callable through inventor_list_baked_tools / inventor_run_baked_tool. The bake database and audit log live locally under %LOCALAPPDATA%\Bimwright\ipt-mcp\baked\. See docs/toolbaker.md and SECURITY.md.

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Not Redistributed

This project does not redistribute Autodesk Inventor binaries or the Inventor SDK / interop DLLs. The shipped server and unit tests build and run with no Inventor present. Building the per-version add-ins requires a local Inventor installation or the matching interop reference assemblies (Autodesk.Inventor.Interop.dll), supplied via the default Autodesk shared-extensions path or an explicit /p:InventorInteropDir=... MSBuild property. Running the gateway against Inventor requires a licensed Inventor install.

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License

Apache-2.0. See LICENSE.

Inventor and Autodesk are registered trademarks of Autodesk, Inc. bimwright is an independent open-source project and is not affiliated with, sponsored by, or endorsed by Autodesk, Inc.