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Fusion - the Fusion 360 Bridge

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Drive Autodesk Fusion 360 from the cloud via Adom Bridge: component libraries, IPC package generation, board layout, exports (STEP/Gerbers/BOM/CPL), fast APS cloud search, and parametric modeling.

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name: fusion-mcp-and-preferences description: >- Use Autodesk's Fusion MCP server (the Autodesk + Anthropic text-to-CAD connector) from an Adom cloud AI, and change ANY Fusion preference including ones the Python API does not expose. The MCP server binds loopback on the user's machine so a cloud container cannot reach it; the fusion bridge proxies it. Covers turning it on for the user (no API exists for the toggle, so the bridge drives the Preferences dialog), the MCP session handshake, the four Autodesk tools, and when to prefer a native fusion_* verb instead. Trigger words - fusion mcp, fusion mcp server, autodesk mcp, claude connector for fusion, text to cad, 127.0.0.1:27182, enable fusion mcp, fusion preferences, change a fusion setting, fusion prefs dialog, api preferences, developer tools fusion, fusion setting not in the api.

Fusion MCP server + preferences

Two capabilities that turned out to be the same trick: Fusion exposes far less to its Python API than to its UI, and the UI is drivable.

The MCP server

Autodesk + Anthropic ship a local MCP server at http://127.0.0.1:27182/mcp exposing Fusion's own text-to-CAD surface.

It binds loopback on the user's machine. An Adom AI runs in a cloud container and cannot reach it. The fusion bridge runs on that machine, so it proxies:

adom-desktop fusion_mcp_status '{}'          # up? serverInfo + live tool list
adom-desktop fusion_mcp_enable '{}'          # turn it ON for the user
adom-desktop fusion_mcp_tools  '{}'          # tools WITH input schemas
adom-desktop fusion_mcp_call   '{"tool":"fusion_mcp_electronics_read",
                                 "arguments":{"entity_type":"electronics.Element"}}'
adom-desktop fusion_mcp_resources '{}'       # electronics entity schemas

Do not ask the user to enable it

It is OFF by default and there is no API for the toggle. fusion_mcp_enable does it for them: opens Preferences, expands General, selects API, ticks the box, Apply, OK, then verifies the port is listening. Tell them it is handled. Only fall back to instructions if the verb reports failure.

The trap that costs a debugging cycle

The setting is discarded unless Apply is clicked. Restart or kill Fusion with the dialog open and it reverts, while the checkbox looked correct. If the port is closed but the user says they enabled it, this is almost certainly why. Re-run fusion_mcp_enable.

The handshake is handled

Streamable-HTTP: a bare POST returns 400 Missing MCP-Session-Id. You must initialize, capture the MCP-Session-Id response header, send notifications/initialized, then pass that header. The bridge does this and re-establishes dropped sessions, so fusion_mcp_call just works.

Autodesk's four tools

tool for the depth is in the params
fusion_mcp_read read/search/see/introspect queryType: projects, document (search/open/recent = file search), apiDocumentation (search Fusion's API docs), screenshot (any view-cube direction), activeCommand (read the live dialog)
fusion_mcp_execute run scripts + document lifecycle featureType: script (arbitrary Python = text-to-CAD), document (open/close/save)
fusion_mcp_update undo / redo only featureType: undo, redo
fusion_mcp_electronics_read read the EAGLE object model entity_type: 49 classes across schematic/board/library + ERC/DRC Error, with object.fields / object.filters / object.pagination

fusion_mcp_resources returns 50 resources: electronics_entity_types plus one electronics_schema_<class> per class (properties, types, filter operators). Read the schema before filtering. Electronics is READ-ONLY; author boards with the native fusion_electron_run. Full write-up: docs/fusion-mcp-server.md.

MCP acts on the active document. Open one first (fusion_aps_open).

MCP vs native verbs

Prefer a native fusion_* verb when one exists. They are tested, they return hints that teach the next step, they handle the awkward parts (kit-aware BOM counting, the 2-minute sign-in clock, GLB optimization), and they work without a Fusion subscription or MCP enabled.

Reach for MCP for Autodesk's text-to-CAD surface and the structured Electronics object model, which is richer for querying a board than anything hand-rolled.

Requirements: Fusion subscription, Fusion running, loopback only.

Any preference, via the UI

The API exposes a thin slice (generalPreferences: theme/orbit/units; apiPreferences: debuggingPort, isDeveloperToolsEnabled). Everything else is UI-only.

adom-desktop fusion_prefs_open  '{"section":"api"}'   # opens + navigates + screenshots
# look at the screenshot, then click what you see:
adom-desktop desktop_click '{"space":"image","shotId":"<from response>","x":690,"y":476,"hwnd":<hwnd>}'
adom-desktop fusion_prefs_close '{"save":true}'       # Apply + OK

Sections: general, api, design, manufacture, electronics, render, drawing, material, graphics, network, preview features.

Why it returns an image instead of control names

Commands.Start PreferencesCommand opens the dialog, and the top-level section tree IS in the UIA tree. But the children under General (API, Design, Manufacture, Electronics, Render, Drawing, Simulation) are rendered lazily by Qt and never appear there, even after desktop_ui_expand reports success. So child navigation is an image-space click, which takes the foreground and is announced with a caption.

Rules

  1. Always finish with fusion_prefs_close {save:true}. Nothing persists otherwise.
  2. Verify the effect, do not trust the click. For MCP, probe the port. For a render setting, observe the change.
  3. Prefer fusion_set_preference for anything in the API-exposed slice; it is background and does not touch the user's screen.
  4. Never leave the dialog open. A modal Preferences window blocks other Fusion verbs.

Full write-ups