autodeskfusion ยท diff
git:20260605.58de7d0 to git:20260606.56b4e15
58 added, 3 removed. Audit C to B.
+ ---
+ name: autodeskfusion
+ description: Use when working with Autodesk Fusion or Fusion 360 through its official local MCP server, including live desktop session inspection, Design workspace model edits, document/body/sketch probes, export checks, and short in-process `adsk` Python scripts. Do not import `adsk` from host Python; execute Fusion API code inside Fusion through MCP or the sim autodeskfusion connector.
+ ---
+
# Autodesk Fusion via MCP
Use this skill when working with Autodesk Fusion through its official local MCP
server. Fusion's `adsk` Python API runs inside the Fusion desktop process, so
prefer short, inspectable MCP calls against the live desktop session.
## Tool Choice
Use the narrowest useful primitive:
- Direct MCP: best for exploration, tool/resource discovery, quick Fusion API
probes, and one-off scripts when the agent can call the MCP endpoint itself.
- `sim connect/exec/inspect`: use when session history, shared `sim serve`
access, standard logs, or plugin discovery make the workflow easier to
resume.
- Host Python: use for saved file parsing, JSON/report post-processing, and
acceptance checks that do not need Fusion's in-process `adsk` modules.
Do not import `adsk` from host Python. If a task needs `adsk`, execute that
code in Fusion through MCP.
## MCP Workflow
1. Keep Fusion open and visible. Human-owned dialogs such as sign-in, account
selection, cloud-save prompts, and first-run setup stay outside automation.
2. Discover the endpoint. Prefer `SIM_AUTODESKFUSION_MCP_URL` when provided;
otherwise try Autodesk's documented default and, if needed, inspect local
- Fusion-owned loopback listeners.
+ Fusion-owned loopback listeners. `http://127.0.0.1:55484/mcp` is a common
+ Fusion MCP URL observed on this machine, but do not hardcode it: the port can
+ change across machines, Fusion versions, or local service conflicts.
3. Call MCP `initialize`, then `tools/list`. Let the returned tool schemas
guide the next call; do not assume a fixed port or permanent tool list.
4. For Python execution, prefer the discovered execute-capable tool, commonly
`fusion_mcp_execute`. Send scripts with a `def run(_context: str)` entrypoint
unless the current tool schema says otherwise.
5. After GUI-visible mutations, capture or request visual evidence before the
next edit.
+ ## Stability Lessons
+
+ - Treat Fusion as a strict CAD kernel, not a tolerant visualizer. Meshes,
+ renderers, and preview tools may display geometry that Fusion rejects as an
+ invalid B-rep, especially near self-intersections, tight curvature, tiny
+ clearances, or very dense paths.
+ - Increase complexity step by step. Start with the smallest inspectable
+ primitive, then add bodies, repeats, detail, and export steps incrementally.
+ After changing a path, size, topology, or API method, return to a small smoke
+ case before rebuilding the full model.
+ - Run cheap host-side gates before asking Fusion to create solids: bounds,
+ units, entity counts, clearance checks, curvature or feature-size checks, and
+ expected export targets. If a gate shows the requested solid is geometrically
+ impossible or marginal, record the limitation instead of forcing the operation.
+ - For near-contact geometry, record explicit contact diagnostics rather than
+ relying on screenshots: nominal feature size, minimum relevant distance,
+ clearance margin, and the sampled/contact pair. Treat intended touching as a
+ small positive CAD margin when the downstream kernel is sensitive to exact
+ tangency.
+ - If a primary Fusion feature constructor fails, try a semantically equivalent
+ native construction only when it preserves the same topology, dimensions, and
+ source geometry. Record both the fallback method and the original failure in
+ metadata so the fallback remains auditable.
+ - Separate model creation from heavyweight export. When a full STEP/archive
+ export risks freezing Fusion, first create the model with export disabled,
+ capture review screenshots or diagnostic markers, then export smaller smoke
+ cases or retry the full export only after the geometry is accepted.
+ - Use short MCP/client timeouts for exploratory calls. If a step fails or times
+ out, reduce scope or switch to a simpler representation; do not keep retrying
+ heavy operations with longer timeouts.
+ - Keep generated Fusion documents under control. Before creating another
+ automation document, close or save prior generated documents as appropriate,
+ and avoid accumulating multiple generated projects in the desktop session.
+ Treat human-owned unsaved work conservatively.
+ - Prefer scripts with explicit runtime options supplied by context or
+ environment variables, such as geometry mode, detail level, sample count,
+ export mode, output tag, and diagnostic simplifications. Do not bake local
+ paths, ports, sizes, or temporary settings into reusable scripts.
+ - If Fusion becomes unresponsive, stop sending more MCP calls. Inspect the
+ process state, restart Fusion only when appropriate, then rediscover the MCP
+ endpoint and resume from the smallest passing step.
+ - Preserve metadata with every export: sources, units, coordinate mapping,
+ build mode, simplifications, bounds, object names/counts, output files, and
+ failure messages.
+
## sim Workflow
From a project environment with the plugin installed:
```powershell
uv run sim check autodeskfusion
- uv run sim connect --solver autodeskfusion --driver-option mcp_url=http://127.0.0.1:55484/mcp
+ uv run sim connect --solver autodeskfusion
uv run sim exec --file path\to\fusion_script.py --label probe
uv run sim inspect mcp.tools
uv run sim disconnect
```
The `mcp_url` option is optional when discovery can find the endpoint. Use it
- when another local service occupies Autodesk's documented default port.
+ when discovery fails or another local service occupies Autodesk's documented
+ default port, for example `--driver-option
+ mcp_url=http://127.0.0.1:55484/mcp` after verifying that port belongs to Fusion
+ on the current machine.
## Script Pattern
Keep scripts small and reviewable:
```python
import json
import os
import adsk.core
import adsk.fusion
def run(_context: str):
app = adsk.core.Application.get()
design = adsk.fusion.Design.cast(app.activeProduct)
result = {
"ok": design is not None,
"document_name": app.activeDocument.name if app.activeDocument else None,
}
out = os.environ.get("SIM_AUTODESKFUSION_OUT")
if out:
with open(out, "w", encoding="utf-8") as handle:
json.dump(result, handle)
return result
```
## Boundaries
- Good targets: Design workspace model edits, document/body/sketch inspection,
export probes, and visible co-editing.
- Do not assume Simulation workspace solve automation exists until a real
`adsk.sim` or MCP probe proves the current Fusion version supports it.
- Keep cloud saves, account state, and vendor licensing decisions human-owned.