Onshape Cad

Onshape CAD CLI

Use this skill to drive Onshape through the repo's CLI. The Python command is onshape-cli; the Node/npm command is onshape. They share command names, flags, and JSON output.

Run Model

• Installed Python CLI: onshape-cli <command> ...
• From this repo without install: python -m onshape_cli.cli <command> ...
• Node package: onshape <command> ... or npx onshape <command> ...
• Every shell call is fresh. Do not rely on aliases, shell functions, or prior exports unless they are set in the same command.
• Every command prints JSON:
  • success: {"ok": true, "result": ...}
  • failure: {"ok": false, "error": ..., "detail": ...}
• Capture feature/document ids from .result with jq; read .detail.message and .detail.notices before retrying failures.

Auth

Create an API key at https://dev.onshape.com -> API keys.

Credential lookup order:

1. --access-key / --secret-key
2. ONSHAPE_ACCESS_KEY / ONSHAPE_SECRET_KEY
3. ~/.onshape/credentials.json or ONSHAPE_CONFIG
4. Linux $XDG_CONFIG_HOME/onshape/credentials.json
5. ~/.claude/mcp.json onshape block

Useful commands:

onshape-cli login
onshape-cli config show
onshape-cli logout

For scripted agents, prefer env vars or explicit flags. ONSHAPE_BASE_URL or --base-url can override the API base URL.

Targeting

Most geometry commands need a document, workspace, and element:

--doc <documentId> --ws <workspaceId> --elem <elementId>

You can also set ONSHAPE_DOC, ONSHAPE_WS, and ONSHAPE_ELEM inside the same shell command. Extract ids from URLs shaped like:

https://cad.onshape.com/documents/<doc>/w/<workspace>/e/<element>

Discovery flow:

onshape-cli list-documents --limit 10
onshape-cli search-documents "name"
onshape-cli get-document-summary --doc D
onshape-cli get-elements --doc D --ws W --type PARTSTUDIO
onshape-cli find-part-studios --doc D --ws W --name "Part"

Free Onshape accounts can create only public documents:

onshape-cli create-document --name "Agent build" --public

The result includes result.id and result.defaultWorkspace.id.

Core Workflow

For new parts:

1. Search before creating, so reruns do not create duplicates.
2. Create or find a document and part studio.
3. Make one clean, closed sketch when possible.
4. Add features and capture returned feature ids.
5. Verify with measure.
6. Render with shaded-view or get-thumbnail.
7. Export only after measurement and visual inspection.

Minimal example:

DOC=$(onshape-cli create-document --name "Bracket" --public | jq -r .result.id)
WS=$(onshape-cli get-document --doc "$DOC" | jq -r .result.defaultWorkspace.id)
ELEM=$(onshape-cli create-part-studio --doc "$DOC" --ws "$WS" --name "Part" | jq -r .result.response.id)
SK=$(onshape-cli sketch-rectangle --doc "$DOC" --ws "$WS" --elem "$ELEM" --plane Top --corner1 0,0 --corner2 3,2 | jq -r .result.featureId)
EX=$(onshape-cli extrude --doc "$DOC" --ws "$WS" --elem "$ELEM" --sketch "$SK" --depth 0.25 | jq -r .result.featureId)
onshape-cli fillet --doc "$DOC" --ws "$WS" --elem "$ELEM" --feature "$EX" --radius 0.1
onshape-cli measure --doc "$DOC" --ws "$WS" --elem "$ELEM"
onshape-cli shaded-view --doc "$DOC" --ws "$WS" --elem "$ELEM" --out render.png
onshape-cli export-stl --doc "$DOC" --ws "$WS" --elem "$ELEM" --out bracket.stl

Geometry Selection

Edges and faces are usually selected with FeatureScript queries evaluated by Onshape. Prefer queries over raw ids unless a command needs an axis or direction.

Common selectors:

• all solid bodies: qAllModifiableSolidBodies();
• faces created by feature: qCreatedBy(makeId("FID"), EntityType.FACE);
• edges created by feature: qCreatedBy(makeId("FID"), EntityType.EDGE);

Shared selection flags:

• --all: all edges on all solid bodies
• --feature FID: edges from a feature
• --circular: circular or arc edges
• --query "<FeatureScript query>"
• --edges id1,id2 or --faces id1,id2

Default plane ids: Front JCC, Top JDC, Right JEC.

Command Map

Documents: list-documents, search-documents, get-document, get-document-summary, create-document, delete-document, update-document, get-elements, find-part-studios, get-workspaces, list-versions, create-version.

Part studios: create-part-studio, delete-element, delete-feature, get-parts, get-features, get-feature-specs, get-sketch-info, get-body-details, validate-partstudio, rollback.

Sketching: sketch-rectangle, sketch-circle, sketch-line, sketch-circle-axis, sketch-candy-cane-path, create-sketch.

Solids: extrude, hole, thicken, revolve, sweep, draft.

Edges/faces: fillet, chamfer, shell.

Booleans/patterns: boolean, boolean-union, mirror, linear-pattern, circular-pattern, offset-plane.

Assemblies: create-assembly, insert-instance, get-assembly-features, assembly-add-feature, assembly-mate-connector, assembly-mate, assembly-group, get-bom, assembly-mass-properties, transform-instance, delete-instance.

Drawings: create-drawing, get-drawing-views, export-drawing.

Feature Studios: create-feature-studio, get-feature-studio, set-feature-studio, get-feature-studio-specs.

Metadata/config: get-metadata, set-metadata, get-variables, set-variable, get-configuration, encode-configuration.

Images/export/measure: thumbnail-info, get-thumbnail, shaded-view, measure, get-edges, find-circular-edges, find-edges-by-feature, mass-properties, export-stl, export.

Raw feature access: add-feature, update-feature, eval-featurescript. Use get-feature-specs first, then pass a BTFeatureDefinitionCall-1406 envelope as --json or --json-file.

CAD Rules That Prevent Bad Builds

• Units are inches; angles are degrees.
• For 3D printing, export-stl is the simplest reliable export. Use export for STEP/IGES/3MF/PARASOLID.
• Cross-document inserts and drawings require a version: run create-version.
• Patterns need real edge ids for --direction-ids or --axis-ids; get them with get-edges.
• Do not chamfer or shell every edge of a body that was already heavily filleted.
• shell needs at least one face to remove.
• revolve and offset-plane can be regen-rejected; inspect featureStatus.
• Prefer one closed profile sketch plus one extrude --op NEW over many fragile additive/removal steps.
• When sketching on Front, sketch X maps to world X, sketch Y maps to world Z, and extrude depth maps to world Y. In measure, bbox.z is height and bbox.y is depth for Front-plane profiles.
• measure verifies dimensions; rendered images verify shape and orientation.
• To edit an existing model, target its existing doc/ws/elem; do not recreate or overwrite it.

Debugging

• ok:false or result.value: null is usually a real API or FeatureScript error, not a transient. Inspect detail.message and detail.notices.
• If a FeatureScript map key conflicts with a variable name, quote the key or use a different key name.
• Seed FeatureScript accumulators with typed zero values when adding measured quantities.
• If unsure about a feature payload, run get-feature-specs and use add-feature or update-feature with JSON.