Fusion 360 MCP Server

This repository provides a Fusion 360 add-in that exposes the active Fusion session through the Model Context Protocol (MCP). It is designed for local coding agents such as Codex that need to inspect, plan, modify, export, and automate both Fusion mechanical design data and Fusion Electronics data from an automated workflow.

Once the add-in is installed into Fusion 360's Add-Ins directory, it can run from there without requiring this development repository to remain in place. The repository is mainly for development, packaging, and testing.

Repository contents

• MCPserve/: Fusion 360 add-in source code.
• MCPserve/MCPserve.py: add-in entrypoint.
• MCPserve/commands/MCPServerCommand.py: main MCP server implementation.
• MCPserve/MCPserve.manifest: Fusion 360 manifest file.
• client.py: local test and smoke-test client for SSE and file-based communication.
• install_mcp_for_fusion.py: helper that installs mcp[cli] and uvicorn into Fusion 360's bundled Python runtime.
• deploy_addin_to_fusion.py: helper that copies the add-in into Fusion 360's user Add-Ins folder.
• AGENTS.md: development and validation guidance for coding agents.

What this server does

The server exposes Fusion 360 data and modeling actions through MCP so an agent can:

• Read the active document, parameters, sketches, bodies, and overall design structure.
• Read the active Fusion Electronics context, including open electronics documents, schematic state, board state, and libraries.
• Create parameters and construction geometry for parametric workflows.
• Create and inspect sketches.
• Add sketch geometry such as points, lines, polylines, circles, rectangles, arcs, and splines.
• Apply sketch constraints and driving dimensions.
• Create 3D features such as extrudes and revolves.
• Create offset planes and reusable modeling references.
• Create components when the active Fusion document supports them.
• Delete bodies created during iterative modeling.
• Export sketches and designs to CAD exchange formats.
• Create electronics sheets and manage electronics transaction boundaries safely.
• Upload and activate electronics projects and library files inside Fusion Electronics.
• Export active electronics schematic, board, and library documents.
• Use prompt helpers for sketch planning, parameter planning, and modeling strategy generation.
• Inspect live Fusion API objects dynamically.
• Execute arbitrary Fusion API Python against the live session when a fixed tool is not enough.
• Execute live Fusion Electronics API and text commands for workflows that do not yet have a fixed dedicated MCP tool.

Communication model

The add-in exposes two communication paths:

1. HTTP SSE at http://127.0.0.1:3000/sse
2. File-based fallback through mcp_comm/

The SSE endpoint is the primary path. The file-based path is intentionally preserved for local testing, recovery scenarios, and clients that cannot attach directly to the HTTP endpoint.

Recent stability improvements:

• File-based commands preserve the full command_<id>.json identifier, including IDs that contain underscores.
• Fusion API work requested through MCP is marshaled onto Fusion's main thread instead of being executed directly from background monitor threads.

Feature overview

Resources

• fusion://active-document-info
• fusion://design-structure
• fusion://parameters
• fusion://components
• fusion://sketches
• fusion://bodies
• fusion://mcp-capabilities

Electronics resources

• fusion://electronics-context
• fusion://electronics-schematic
• fusion://electronics-board
• fusion://electronics-library
• fusion://electronics-libraries
• fusion://electronics-documents
• fusion://electronics-errors

Modeling tools

• message_box
• create_new_sketch
• create_parameter
• create_component
• create_offset_plane
• list_sketch_entities
• list_sketch_profiles
• create_sketch_point
• create_sketch_line
• create_sketch_lines
• create_sketch_circle
• create_sketch_rectangle
• create_sketch_center_rectangle
• create_sketch_arc
• create_sketch_spline
• add_sketch_constraint
• add_sketch_dimension
• create_extrude
• create_revolve
• delete_body

Export tools

• export_sketch_dxf
• export_design_file
• export_active_drawing_pdf

Generic bridge tools

• inspect_fusion_object
• execute_fusion_api

Electronics tools

• create_electronics_sheet
• begin_electronics_change
• end_electronics_change
• cancel_electronics_change
• list_electronics_documents
• upload_electronics_project
• open_electronics_document
• activate_electronics_document
• export_electronics_file
• execute_text_command
• execute_electronics_api

Prompt helpers

• create_sketch_prompt
• parameter_setup_prompt
• feature_strategy_prompt

Advanced workflow coverage

This project is not limited to a minimal sketch demo. The current implementation supports a broader automation workflow:

• Parametric setup with named user parameters.
• Construction-plane creation for stacked or offset modeling operations.
• Sketch authoring with token-based entity tracking.
• Constraint-driven sketch refinement.
• Dimension-driven profile control.
• 3D solid generation through extrude and revolve features.
• Iterative cleanup by removing obsolete bodies.
• Export to STEP, IGES, SAT, STL, 3MF, OBJ, DXF, and drawing PDF.
• File-based fallback commands for smoke testing even when direct MCP transport is unavailable.
• Main-thread dispatch for Fusion API calls to reduce instability during heavier modeling or export operations.
• Dynamic live inspection of Fusion API objects, collections, and selected entities.
• A general-purpose execution bridge for unsupported or newly needed Fusion API features without waiting for a dedicated MCP tool.
• Fusion Electronics context inspection for active schematic, board, library, and project documents.
• Electronics document upload and activation workflows for SCH, BRD, LBR, and their Fusion-managed FSCH, FBRD, FLBR, and FPRJ counterparts.
• Electronics sheet creation and explicit transaction control for safer scripted edits.
• Round-trip export of live Fusion Electronics documents back to electronics file formats.
• A live electronics execution bridge for schematic and board automation when a dedicated tool is not yet present.

Runtime mode

The add-in supports two practical modes:

1. Development mode: run from this repository while editing code and using helper scripts.
2. Installed mode: run directly from Fusion 360's user Add-Ins folder with Codex or another MCP client, without depending on this repository path.

In installed mode, the add-in still creates runtime artifacts such as mcp_comm/ and export output near the installed add-in when needed.

Requirements

• Autodesk Fusion 360
• Windows or macOS
• Python 3.7+ for client.py, deploy_addin_to_fusion.py, and install_mcp_for_fusion.py
• mcp[cli] and uvicorn installed inside Fusion 360's bundled Python

Installation

1. Install Python packages into Fusion 360's Python

Fusion 360 ships with its own Python runtime. MCP must be installed there, not only in your system Python.

Recommended:

python install_mcp_for_fusion.py

Manual fallback:

"[Fusion Python Path]\\python.exe" -m pip install "mcp[cli]" uvicorn

2. Install the add-in into Fusion 360

Option A, manual import:

1. Open Tools -> Scripts and Add-Ins.
2. In My Add-Ins, click the green +.
3. Select the MCPserve folder from this repository.
4. Run the add-in named MCP Server.

Option B, copy into Fusion's Add-Ins folder:

python deploy_addin_to_fusion.py

Then open Fusion 360 and run MCPserve from Tools -> Scripts and Add-Ins.

Codex and agent workflow

This repository is prepared for agent-driven development and testing.

• Read AGENTS.md first for execution boundaries.
• Edit the repository normally.
• Run syntax checks locally.
• Run functional validation inside Fusion 360 because the adsk API only exists there.

Recommended checks:

python -m py_compile client.py install_mcp_for_fusion.py deploy_addin_to_fusion.py MCPserve\MCPserve.py MCPserve\commands\MCPServerCommand.py MCPserve\lib\fusionAddInUtils.py
python client.py --wait-ready --test-connection
python client.py --list-resources --list-tools --list-prompts

For direct MCP use from Codex, the most important requirement is that Fusion 360 is open and the MCPserve add-in is running. After that, a client can connect directly to http://127.0.0.1:3000/sse.

Client usage examples

Basic connection test:

python client.py --wait-ready --test-connection

List MCP objects:

python client.py --list-resources
python client.py --list-tools
python client.py --list-prompts

Read a specific resource:

python client.py --test-resource fusion://bodies
python client.py --test-resource fusion://mcp-capabilities

Run simple tool tests:

python client.py --test-message-box --message "Hello from Fusion MCP"
python client.py --test-sketch --plane XY
python client.py --test-parameter --param-name Width --param-expression 25 --param-unit mm

Force a specific file-based communication directory:

python client.py --comm-dir .\MCPserve\mcp_comm --list-tools

Generic Fusion API bridge

The server now includes a generic execution path so an MCP client is not limited to the fixed built-in tool list.

• inspect_fusion_object inspects a live object path such as design.rootComponent.features, root_component.sketches, or cam.setups.
• execute_fusion_api runs Python inside the live Fusion session with useful prebound objects and helpers.

The execution context includes:

• app, ui, doc, active_product
• design, drawing, cam
• root_component
• selected_entities, selected_tokens
• find_component, find_sketch, find_body, find_plane, find_axis, find_entity
• find_profile_entity
• point3d, point2d
• length_value, length_input, angle_value, angle_input
• exports_dir, comm_dir
• state for lightweight cross-call memory

This means a Codex session can reach most of the public Fusion API surface even if a dedicated MCP tool has not been implemented yet.

Fusion Electronics support

The server now includes a first-class Fusion Electronics layer in addition to the mechanical modeling tools.

• fusion://electronics-context reports the active electronics product state and linked documents.
• fusion://electronics-schematic and fusion://electronics-board provide lightweight live summaries that are safer to query repeatedly than deep raw serialization.
• list_electronics_documents, open_electronics_document, and activate_electronics_document help recover and control active FSCH, FBRD, FPRJ, and FLBR documents.
• upload_electronics_project supports loading external electronics content into Fusion-managed documents.
• export_electronics_file supports exporting the active live electronics document back out for handoff, verification, or versioning.
• execute_electronics_api and execute_text_command provide an escape hatch for advanced electronics workflows that do not yet have a fixed MCP tool.

In practice, this means a Codex workflow can inspect existing Fusion Electronics projects, create or activate sheets, upload generated electronics files, reopen them inside Fusion, verify their live schematic and board state, and export the result again without leaving the MCP loop.

Troubleshooting

• If Fusion cannot import the add-in, confirm that MCPserve/MCPserve.manifest exists and matches the folder name.
• If the add-in starts but the client cannot connect, inspect mcp_comm/server_status.json and mcp_comm/mcp_server_error.txt.
• If the SSE endpoint is unavailable, use the file-based path from client.py.
• If package imports fail inside Fusion, rerun install_mcp_for_fusion.py against Fusion's bundled Python.
• If the active document is a single-part design, component creation may be limited by Fusion 360 document rules.
• If a needed feature is not covered by the fixed tools, use the generic bridge described above instead of treating it as unsupported.
• If Fusion Electronics reports an intermittent document-validation error while opening an uploaded project document, inspect fusion://electronics-documents and activate the schematic or board document directly. The linked documents may still be valid even when the project wrapper reports a Fusion-side validation issue.

References

• Fusion 360 API: Creating a Script or Add-In
• OpenAI Codex Help Center