Kernelcad MCP server

• add_connectorFree

  Use this when you need to add a mate connector to a part. Durably insert `<partBinding>.connector(name, { type, origin, axis?, normal? })` before the final top-level return. Use the part binding returned by add_part. Returns modified source plus diagnostics from re-evaluation. Side-effect-free.

• add_constraintFree

  Use this when you need to add a sketch constraint to a list. Append one validated sketch constraint to a constraint list. Side-effect-free: pass { constraints, constraint } and receive the updated list.

• add_curveFree

  Use this when you need a freeform/organic 3D curve — a body feature line, brow, spine rail, or G2 blend between panels — authored as a Curve3D into the user's .kcad.ts immediately before the last top-level return. One authoring path, selected by `kind`: - 'nurbs' — insert a `nurbsCurve(controlPoints, opts?)` declaration. Pass `controlPoints` as a Vec3[] (mm, at least 2 points). Optional NURBS knobs: `degree` (default 3), rational `weights`, explicit `knots`, `closed`. - 'hermite' — insert a `hermiteG2(a, b)` declaration: a quintic Hermite curve interpolating two endpoints with matching positions, tangents, and (optional) curvatures — bridges two curves with G2 continuity. Each endpoint is `{ point: Vec3, tangent: Vec3, curvature?: Vec3 }` in mm; tangent magnitude ~ chord length; curvature defaults to [0,0,0] (G1-only). The returned binding has type Curve3D (peer to Shape / Surface) — consume it via `add_variable_sweep` (spine input), `add_surface({ kind: 'boundary' })` (boundary curve), or downstream Curve3D-accepting features. Returns the modified code + diagnostics from re-evaluating. Side-effect-free. Each kind fails closed on its own missing required params.

• add_featureFree

  Use this when you need to insert a new feature line into a script. Insert a new feature line into a kernelCAD script before the last top-level return statement. Returns the modified code as text plus diagnostics from re-evaluating the result. Side-effect-free. Primitives that accept faceLabels (box, cylinder, extrudeRect, extrudeCircle, extrudePolygon, extrudeRoundedRect) can receive `opts.faceLabels` in the inserted code — use `lookup_api` to see `featureKindFaceLabels` for the full value schema.

• add_mateFree

  Use this when you need to author a mate-graph relationship into the source, selected by `relation` (default 'mate'): - 'mate' — a typed mate between two connectors ({ name, a, b, type, pose?, limitsDeg?, limitsMm? }). - 'coupling' — couple a driven mate to a source mate by ratio ({ driven, source, ratio, offset? }). - 'transmission' — a physical drive path across mates ({ name, kind, sourceMate, drivenMates, path, ... }). All durably edit source and need { code, assembly_binding }. Params other than `relation` are forwarded verbatim; each relation fails closed on its own missing required params.

• add_partFree

  Use this when you need to add a part to an assembly. Durably insert `const <binding> = <assembly>.part(partName, shapeExpression, opts?)` before the final top-level return in a kernelCAD source string. Returns modified source plus diagnostics from re-evaluating it. Side-effect-free: caller persists the returned source.

• add_path_segmentFree

  Use this when you need a freeform/organic 2D outline — an eyewear brow, ergonomic grip, sneaker midsole, or body silhouette — by appending a curved segment to an existing PathBuilder chain on the named `chain_anchor` variable. The call is injected at the END of the chain, immediately before any `.close()`. One segment kind, selected by `kind`: - 'spline' — `.spline(points, opts?)`: interpolates through every `points` waypoint (Vec2[] mm, >= 2 entries; points[0] must match current pen position). Optional `tension`, and `startTangent`/`endTangent` 2D direction vectors that constrain the first-derivative direction at the endpoints (magnitude normalised internally). Use for organic 2D outlines (eyewear brow, ergonomic handle, sneaker midsole). - 'nurbs' — `.nurbsSegment(controlPoints, opts?)`: explicit B-spline net (Vec2[] mm, >= degree+1 entries; controlPoints[0] must match pen; pen ends at controlPoints[N-1]). Optional `degree` (default 3), rational `weights` (strictly positive), explicit `knots` (length = controlPoints.length + degree + 1). - 'hermite' — `.hermiteG2(a, b)`: each endpoint `{ point: Vec2, tangent: Vec2, curvature?: Vec2 }` in mm (a.point must match pen; pen ends at b.point). `curvature` defaults to [0,0] (G1); pass matching curvatures for G2 blends. Tangent magnitude is the first derivative (~ chord length), NOT unit length. Returns the modified code + diagnostics from re-evaluating. Side-effect-free. Each kind fails closed on its own missing required params.

• add_pattern_featureFree

  Use this when you need to repeat a feature in a pattern. Insert a Shape.patternLinear / .patternCircular / .patternGrid call into a kernelCAD script before the last top-level return. Pass structured args (kind + the matching spec object). Returns the modified code plus diagnostics from re-evaluating. Side-effect-free. The pattern feature is a single editable unit; pattern-instance face refs resolve via `<sourceId>_pattern_<i>` on the pattern feature's lineage. Geometric note: pattern is implemented as cumulative boolean union of transformed source copies — additive features (boxes, ribs, fins, spokes) pattern cleanly; patterning a subtractive feature (hole, cutout) only preserves the per-instance void when adjacent bodies are disjoint.

• add_surfaceFree

  Use this when you need an organic, freeform, or swept shape — a body shell, panel, fairing, ergonomic curve, lens, or sculpted form — authored as a NURBS Surface into the user's .kcad.ts, OR when you need to finish surfaces into a watertight solid or taper faces for moldability. One authoring/finishing path, selected by `kind`: - 'nurbs' — insert a nurbsSurface(...) / surfaceFromCurves(...) call. Pass either { controls, degree, weights?, knots?, periodic? } for direct construction, OR { section_sketch_ids } for skinning. Weights are honored: supply rational weights to build exact circles/cylinders/spheres/conics (the surface becomes rational); omit weights for a non-rational surface. - 'boundary' — insert a surfaceFromBoundary([c1,c2,c3,c4], opts?) call: one NURBS face through 4 boundary Curve3D refs (bottom, right, top, left in loop order; adjacent endpoints must coincide within 1e-6 mm) via OCCT BRepOffsetAPI_MakeFilling. - 'trim' — insert a `<surface>.trimTo(<by>)` or `<surface>.split(<by>)` call. Pass `surface_binding` (the Surface variable name), `by_binding` (the cutter Surface variable name; Shape/Curve3D cutters are deferred to a later slice), and `op: 'trim'` (keep the largest imprinted piece) or `op: 'split'` (return both halves as a `[Surface, Surface]` tuple). - 'sew' — insert a `sew([s0, s1, ...], opts?)` call to stitch N surfaces into a closed watertight solid via OCCT BRepBuilderAPI_Sewing. Pass `surface_bindings` (array of Surface variable names). Use after trim/boundary to close patches into a solid: trim → sew → solid pipeline. Optional `tolerance` (mm, default 1e-6) and `require_closed` (emits feature.surface-sew.open-shell if result is not watertight). - 'draft' — insert a `<shape>.draft(angleDeg, { face, neutralPlane?, pullDir? })` call to taper the selected face(s) for mold release. Pass `shape_binding`, `angle_deg` (0–90), and `face` (canonical name, label, or FaceQuery descriptor). Lowering emits feature.draft.failed on invalid geometry. The returned Surface produces no Shape until you chain .thicken(t) or .toShape() (do that via add_feature on the binding name). Returns the modified code + diagnostics. Each kind fails closed on its own missing required params.

• add_textFree

  Use this when you need to author text into a kernelCAD script before the last top-level return. One authoring path, selected by `mode`: - 'sketch' — insert a sketch.text(...) call. The emitted sketch is chainable: pair with subsequent .extrude(...) / cut(...) edits to land an engraved or raised text feature. - 'emboss' — insert a `<shape>.embossText({...})` chained call onto an existing Shape `target`. Use for engraved brand text on faces (Ray-Ban temple, CE mark, model number). `depth > 0` raises text out of the face; `depth < 0` engraves text into the face. Lowers via replicad drawText → sketchOnFace → extrude → fuse|cut. Default font is the runtime-bundled Liberation Sans. Side-effect-free; returns the modified code plus diagnostics from re-evaluating. Each mode fails closed on its own missing required params.

• add_variable_sweepFree

  Use this when you need an organic swept solid whose cross-section changes along its length — a tapering body, horn, bottle, fairing, or duct — authored as a variable-section sweep along a spine. Insert a `variableSweep(spine, sections, opts?)` declaration into the user's .kcad.ts immediately before the last top-level return. The result is a Shape — chain `.translate(...)`, `.union(...)`, etc. via `add_feature`. `spine_binding` references an existing variable (Curve3D / Sketch / Vec3[]) in the source; each `sections[i].profile_binding` references an existing Sketch. Sections must be strictly increasing in `t` and span [0, 1]; first t=0, last t=1. Orientation is not exposed by this MCP tool until runtime orientation support is wired. Validates every binding exists in the source via regex before inserting (fast structured error vs capture-time stack). Returns the modified code + diagnostics. Side-effect-free.

• add_workspace_targetFree

  Use this when you need to declare a reachability target for a connector. Durably insert `<assembly>.workspace(connectorRef, { reachable, toleranceMm? })` before the final top-level return. Workspace targets are checked by solvedModel validation/review pose-envelope gates. Returns modified source plus diagnostics from re-evaluation.

• capture_animationFree

  Use this when you need to render a script's animation timeline to a video. Capture a kernelCAD script's animationView({...}) timeline to an MP4 (ffmpeg) or a PNG frame sequence, verifying the sampled poses for part interference. FILE ONLY: pass { file } (a .kcad.ts path) — there is no { code } mode, because the capture engine renders from a file on disk (its relative lib.fromSTEP imports resolve against the script directory). MP4 by default; pass { frames_dir } to write frame-0000.png... and skip ffmpeg entirely (mutually exclusive with output_path). Animation-pose interference verification runs by default (keyframe times + segment midpoints) BEFORE any browser/ffmpeg cost; { no_verify: true } skips it and { verify_every: n } additionally samples every n-th frame time. Pass { focus } or { hide } (arrays of feature ids or assembly part names, mutually exclusive) to isolate parts in the rendered frames — same semantics as `kernelcad render --focus/--hide`; visibility is render-only and does NOT affect the pose verification. Collisions DO NOT fail the call — the artifact is still written as evidence with ok: true; read verified: false + the collisions[] array. ENVIRONMENT REQUIREMENT (identical to `kernelcad render`): capture drives a headless browser against a running studio dev server reachable at http://localhost:5173 (or the VITE_PORT override); there is no bundled-static serving mode yet, so the same dev-server precondition applies in a production MCP install. Returns { ok, output_path, frame_count, duration_ms, fps, verified, verify_skipped?, collisions: [{ t_ms, a, b, volume_mm3 }], diagnostics }.

• design_loopFree

  Use this when the goal is complex / production / enclosure / gearbox / robot-arm / multi-body, or when you need evaluate→review/verify→revise until green. PREFERRED over one-shot evaluate_script+open_in_studio for Adam-level parts. Runs a CAD design loop over attempt scripts: review_cad each attempt, continue past functional attempts with unresolved warnings, return repair prompts (nextActionPrompt) plus structured revisionAssist (suggestedPatches / autoApplied.suggestedCode for repairable feature failures; cookbook steers for stacked-primitive toys). Stop on ok or convergence.escalate. For organic/car bodies set likenessProfile:"automotive" and pass bodyLikeness (or automotive stills on visualReview.checks) — attempts fail closed until body-likeness is publishReady. Optionally write a Studio build record JSON.

• diff_geometryFree

  Use this when you need to know WHAT MATERIAL changed between two versions of a model, not just how much. The deeper sibling of diff_scripts: a volume delta alone is ambiguous (a boss that grew and a pocket that deepened report the same magnitude, and a part that only moved reports zero), so this tool answers it with geometry instead of pixels. Baseline is { baseFile } or { baseCode }; the revised side is either another script ({ file } or { code }) or the SAME script re-lowered with { params } overrides — a bag of declared param() name -> new value, which is the one-script form a parameter sweep actually asks for. Bodies pair by name and fall back to declaration-order positional pairing; anything left over is listed in `unmatched` and raises diff.body.unmatched. Per matched body it returns addedMm3 = volume(revised - base), removedMm3 = volume(base - revised), commonMm3 = volume(base ∩ revised) from OCCT booleans, exact bbox with min/max/extent deltas, face / edge / hole count deltas (hole counts reuse the cylindrical-hole detector), maxDeviationMm (two-sided discrete Hausdorff distance between the two surfaces), and a `verdict` — identical | moved | resized | topology-changed, precedence topology-changed > resized > moved > identical. Branch on the verdict; cite the numbers. Optional { render: true } also writes an overlay PNG (added green, removed red, unchanged material as a translucent ghost; the scene is a re-runnable .kcad.ts over lossless BREP sidecars) through the render_preview pipeline and fails open (the numeric diff is still returned) when that pipeline is unavailable. Read-only — never touches the active session.

• diff_scriptsFree

  Use this when you need to see exactly what changed between two script versions. Structured geometric delta between two versions of a kernelCAD script — a baseline ({ baseFile } or { baseCode }) and a revision ({ file } or { code }). Returns agent-readable JSON: per-part added/removed/renamed/changed (volume mm³ + exact bbox deltas, numbers matching inspect({ of: 'part-stats' })), total interference-volume delta with per-pair detail, mate-graph changes (added/removed/changed mates incl. type, connectors, pose, limits), and param changes (value/min/max). Single-shape scripts diff as one "(root)" pseudo-part. Use after editing a script to verify exactly what changed physically before re-rendering. Read-only — never touches the active session.

• drawing_to_cadFree

  Use this when the reference for a part is a 2D engineering drawing PDF (orthographic views with dimensions), not a photo. Deterministic, no vision model: reads the vector linework (stroke width, dash) and positioned text; classifies visible / hidden / center / dimension / extension lines; reads the title block scale, units and projection symbol; identifies front / top / side views by projection alignment (third- or first-angle); ties dimension text to its lines (⌀, R, 4×, ±, THRU, depth). Dimension values win over measured lengths. Rebuilds the part as the view silhouette extruded by the depth an orthogonal view shows, or a turned part revolved from its half-silhouette, plus holes from ⌀ circles with THRU or hidden-line depth. Returns `script` — a `.kcad.ts` with role-named params (width, thickness, holeDia, hole1X, dia1, step1Length …) — and `ledger`, an assumption ledger where stated dimensions are `visible`, symmetry-derived positions `inferred`, defaults `assumed` and an unstated depth `missing`; a dimension that disagrees with the linework keeps its value and records the disagreement as an open fact. With verify (default) the script is evaluated, re-projected through the svg-drawing view stage and compared: `fidelity.verdict` is match | partial | mismatch | failed with per-axis extents, hole diameters and per-view silhouette IoU. Pass `out` to write the script and its `<stem>.ledger.json` (resolve open facts with resolve_assumptions, then set_param). A scanned (raster-only) page fails with reference.drawing.raster-only — use trace_from_image for those.

• evaluate_scriptFree

  Use this when you need to run a script and check it compiles. Run a kernelCAD .kcad.ts script and report pass/fail + feature count + diagnostics. When the scene is assembly-built (assembly().part(...) → .model()/.solvedModel()), also returns a parts summary { count, names } AND runs the mechanism-truth gate by default: the `mechanism` field reports real/broken/unverified and a broken mechanism (disconnected components / mechanism.orphan-part, self-collision, fastened drift, dof-mismatch) makes ok:false with the failures in diagnostics — multi-body assemblies need connectors + mates/joints (axis+revolute for shafts/hinges/gears; frame+fastened for rigid; or arm.revolute/.prismatic/.ball/.fixed). Pass { skipMechanismCheck: true } to opt out. Pass either { file: "<path>" } or { code: "<inline source>" }. Set { dryRun: true } for fast validation while iterating: transpile + capture + capture-light checks WITHOUT OCCT lowering, DFM gates, or meshing — milliseconds instead of seconds (100x+ on boolean/fillet-heavy scripts). A dry run catches script throws, capture-time API misuse, and assembly validity-gate failures, but NOT lowering failures or dfmSpec diagnostics; it leaves the active session untouched, so finish with a full (non-dry) evaluate_script before using session-dependent tools.

• evaluate_sdfFree

  Use this when you need to sample a signed-distance field at a point. Sample the signed distance from an in-script sdf.* field at a 3D point. Returns { distance, inside, aabb, kind }. Distance is in mm; negative = inside the surface, 0 = exactly on the surface, positive = outside. Use this to verify SDF composition before calling sdf.materialize (which is the expensive step). The script must bind the SdfField via sdf.bind('<name>', field) and pass that name as fieldName. Hint: pass either { file } or { code }, plus { fieldName, point: [x,y,z] }.

• exportFree

  Use this when you need to export geometry to a file. One exporter, selected by `target`: - target:'model' — export the script geometry to one file. Pass { file | code }, a required { output_path }, and { format }. Supported formats: stl (binary STL mesh), step (BREP CAD interchange), dxf (planar laser/waterjet profile from a Region or planar face), 3mf (slicer-friendly mesh with per-part colors), glb (web-viewer / AR with PBR materials), svg-drawing (third-angle engineering-drawing sheet: front/top/left + isometric views, hidden edges dashed, tangent edges thin, overall bounding-box dimensions, title block; assemblies are drawn with inter-part occlusion; pass options.annotations to dimension specific features instead of the bounding box; pass options.exploded { factor, mode } to explode the isometric cell, options.balloons to number parts from the BOM, and options.partsList for an item/name/qty/material table above the title block). overall bounding-box dimensions, title block; assemblies are drawn with inter-part occlusion; pass options.annotations to dimension specific features instead of the bounding box, options.autoAnnotate to derive datums A/B/C, grouped hole callouts with position tolerances, hole positions, overall size, radius and chamfer callouts, flatness and an ISO 2768 note from the geometry (the result carries drawing_report with placed / overlapped counts), and options.sections for real section views on any cutting plane). Robot descriptions: urdf (tree-topology robot description), srdf (motion-planning semantics layered over the URDF), sdf-gazebo (SDFormat 1.10 with native ball joints, closed loops, and solved per-link poses), usd-isaac (ASCII USD physics stage: PhysicsArticulationRootAPI root, one rigid body per link at its solved pose with mass / centre of mass / principal inertia, PhysicsFixedJoint/PhysicsRevoluteJoint/PhysicsPrismaticJoint per mate with token axis, two-sided joint frames and limits, UsdPreviewSurface materials from the part appearance, and joint drives only when declared in options.drives { <mate>: { stiffness, damping, maxForce?, targetPosition? } }; options.collisionApproximation is convexHull | convexDecomposition; planar/cylindrical/pin_slot/ball mates fail closed with export.usd.joint-unsupported). bom-csv / bom-json (bill of materials over assembly.model()/solvedModel(): one row per distinct part — grouped by geometry/catalog identity, not name — with real instance quantity, kind, material, density, mass, bbox, process hint, and catalog provenance for purchased parts; same numbers as inspect({ of: 'bom' })). urdf and sdf-gazebo also write one meshes/<part>.stl per link, and usd-isaac one meshes/<part>.usda mesh layer per link, next to output_path (reported in mesh_files) — ship the whole directory to the consumer. STL exports run a watertight verify by default; failures return ok: false with export.mesh.not-watertight (open-edge count + up to 5 crack-cluster locations) but the file is still written so the broken mesh can be inspected. Optional { feature_id } selects which feature to export (default: last). Optional { options } carries per-format options bag (see the kernelcad-mcp skill for the per-format keys: dxf layers/tolerance/unit, 3mf printUnit/embedSource, glb axis/draco). - target:'part' — export solved-assembly parts as individual binary STL files in their modeled (world-frame) positions. Pass { file | code }, plus { part, output_path } for one part or { output_dir } for all parts (files land at <output_dir>/<part>.stl). A watertight verify runs on every exported mesh by default and fails the call with export.mesh.not-watertight; unknown part names fail with export.part.not-found listing the valid names. Pass { no_verify: true } to skip the watertight gate. All params except `target` are forwarded verbatim; each target fails closed on its own missing required params.

• fea_summaryFree

  Use this when you need a structural check's context without paying for a solve. Read-only: returns the stored summary of a previous run_fea (pass the same `output_dir`), whether the CalculiX + gmsh toolchain is available on this machine (with the install command when it is not), and the FEA material table with real E / Poisson / yield numbers so a grade is chosen against data rather than from memory. Never meshes, solves, or writes.

• fetch_partFree

  Use this when you need to download a catalog part as a STEP file. Resolve an id (or single-match query) to a part record and write its STEP file to the local cache. Bundled ids resolve offline; non-bundled ids require partsBaseUrl (or KERNELCAD_PARTS_BASE_URL). Returns the cache path plus a sha256 fingerprint.

• find_partFree

  Use this when you need to find a part in the catalog. Discover bundled (and optionally remote) part-catalog records by fuzzy query and faceted filters. Tokens AND-combine; cross-facet filters AND-combine. Pass partsBaseUrl (or set KERNELCAD_PARTS_BASE_URL) to enable the remote tier; otherwise results are bundled-only.

• flatten_patternFree

  Use this when you need the unfolded flat pattern of a bent sheet-metal part. Return the unfolded 2D flat-pattern of a bent sheet-metal Shape as a Region (outer polyline + holes + bend lines + sketch plane). Slice 1: at most 2 bends. Pass { file } or { code }; optional { featureId } to pick a specific Shape.

• get_latest_renderFree

  Render a project's current model server-side and return it as an inline image so you can SEE what you built. Prefer open_in_studio for the happy path — it already includes an iso PNG preview in the same publish result when previewDelivered is true. Use this tool for a different `view`, a contact sheet (`view:"all"`), or when you only have a slug and are not publishing. Call with that `slug` to inspect whether the build looks right. CRITICAL — the image is rendered from the MODEL on the server; it does NOT reflect the user's Studio camera, zoom, or screen. NEVER ask the user to rotate, zoom, pan, move the camera, close a slider, or change their view to help you see — you cannot affect their screen and it cannot affect this render. To see a different angle, call this tool again with a different `view`. By DEFAULT (omit `view`, or `view:"all"`) it returns a CONTACT SHEET of all six canonical views in one labeled image — a 3×2 grid, top row [iso, front, right], bottom row [back, left, top] — so you can judge the model from every side regardless of its orientation (e.g. to find which side has the doors). Pass a single `view` (iso/front/back/left/right/top) for one large render of that angle. DETERMINISTIC: the same model + view always returns the same bytes — identical bytes are NOT a stale/lagging snapshot. If you changed the model, push it with open_in_studio FIRST, then re-render to see the change. The image is always current and never a blank capture. Colors and shading match Studio (same palette / base-material color). The slug is the capability: no OAuth for public/unlisted; private projects require the owner signed in. The PNG is base64-inlined as a real image block by default; pass `paths_only: true` for metadata only. No renderable geometry or a mesh failure → { ok: false, error, hint }, never a blank image.

• get_model_meshFree

  Return the raw per-feature triangle mesh (positions/indices/normals) of a project's current model, by slug. For the in-chat 3D viewer widget to render geometry; delivered over the MCP Apps bridge. The slug is the capability: public/unlisted need no OAuth; private requires the owner signed in.

• get_projectFree

  Use this when you need to reopen a saved project or browse what the user has saved — it fetches a kernelCAD Studio project, or lists the signed-in user's saved projects. Pass `slug` (from a /p/<slug> link or a prior listing) to fetch that project's full .kcad source and metadata — then edit and open_in_studio with the same slug so the user's open tab updates live. Private projects require their owner's OAuth connection. OMIT `slug` to list the signed-in user's saved projects (most recently updated first); that listing mode requires the OAuth connection and does NOT paint. Paint phases: projectSaved/meshReady reflect fetch state; viewerPainted stays false until the widget acks display. Prefer open_in_studio (with code) to publish+paint — do NOT call get_model_mesh or get_latest_render for interactive paint.

• get_project_revisionFree

  Fetch the exact immutable .kcad source and parameters captured at a prior `open_in_studio` version. Use this to read-after-write verify a release: pass the returned `slug` and `version`, then hash or inspect the returned source. Public/unlisted projects use the slug as capability; private projects require the owner's OAuth connection.

• inspectFree

  Use this when you need to read facts about a model. One reader, selected by `of`: - 'assembly' — physical assembly inventory (parts, bboxes, connectors, mates, disconnected solids). - 'robot' — URDF/SDFormat export preview (links, joints, planning groups, end-effectors, issues). - 'step' — inspect an imported STEP file. - 'shape' — volume / surfaceArea / bbox for one feature ({ feature_id? }). - 'mass' — mass, centre of mass, centroidal inertia tensor (inertia6 + 3x3 inertiaMatrix), principalMoments/principalAxes, symmetry flags, and optionally the radius of gyration about an arbitrary axis ({ feature_id?, density?, gyration_axis? }); density in kg/m^3, defaults to 1000 (water). - 'features' — features captured by the script (kind, id, params, transforms, suppression). - 'assemblies' — assembly intent (assemblies, parts, connectors, joints). - 'topology' — canonical face names + edge count for a feature ({ feature_id? }). - 'edges' — edges of a shape with optional EdgeQuery ({ feature_id?, query? }); returns @kc[...] refs. - 'face-edges' — boundary edges of a named canonical face ({ feature_id?, face_name }). - 'faces' — faces of a shape with optional FaceQuery ({ feature_id?, query? }); returns @kc[...] refs. - 'face-labels' — user-applied labels visible in the script. - 'mates' — mates captured by the script. - 'constraints' — sketch constraints captured by the script. - 'part-stats' — bundled parts-catalog statistics. - 'bend-table' — sheet-metal bend table for a flattened pattern. - 'params' — declared model parameters. - 'part-categories' — top-level part-catalog categories available in the bundled (and configured remote) catalog. - 'part-families' — part families within a category ({ category? }); count + exemplar ids per family. - 'bom' — bill of materials ({ assembly? }): one row per distinct part (grouped by geometry/catalog identity, not name) with real instance quantity, kind ('fabricated'|'purchased'), material, density, per-unit and total mass, bbox, a fabrication process hint, catalog provenance for purchased parts, and totals; `bom.*` diagnostics flag rows with no density source or missing catalog vendor info instead of guessing. - 'section' — numeric cross-section probe of a shape: area, perimeter, loop/hole counts, 2D bbox at a plane ({ feature_id?, plane | at+axis, stack?: { from, to, count, axis? } }). `stack` scans evenly spaced slices and returns `minAreaIndex`/`minAreaPosition` — use it to find the neck/thinnest cross-section along an axis. - 'continuity' — G0/G1/G2 classification of shared edges ({ feature_id?, edges? }); position gap, normal jump, curvature difference, worst-sample XYZ. - 'curvature' — per-face Gaussian and mean curvature min/max/mean, inflections, spikes ({ feature_id?, faces?, spike_factor? }). All params except `of` are subject-specific and forwarded verbatim. Most subjects accept { file | code }.

• lookup_apiFree

  Use this when you need to list the kernelCAD script-runtime surface: global functions (box, path, selectEdges, helix, etc), Shape methods (fillet, sweep, lower, etc), Sketch methods (extrude, revolve, sweep), PathBuilder methods, EdgeQuery/FaceQuery key sets, and featureKindFaceLabels (which globals accept opts.faceLabels and valid value shapes). Use this to discover what is callable from a .kcad.ts script. Call this BEFORE concluding kernelCAD lacks a capability — its NURBS freeform surfacing (loft, sweep, boundary-fill, G2 blend) is easy to miss from tool names alone.

• lookup_authoring_skillFree

  Return the kernelcad-authoring SKILL.md body — conventions for writing .kcad.ts scripts (imports, parameters, evaluation contract, common pitfalls). Use this tool BEFORE generating CAD code if your MCP client does not list resources. Clients that do list resources should instead read `kernelcad://skills/authoring` directly — the contents are identical. INPUT: none. OUTPUT: { uri, mimeType, text } where `text` is the SKILL.md body.

• lookup_cookbookFree

  Use this when you need a canonical pattern snippet for a CAD task. Search the kernelCAD cookbook for canonical pattern snippets. Returns top-k snippets matching the natural-language query, ranked by BM25 over title/tags/keywords/trigger. Use when you need a canonical pattern for fillet-after-subtract, non-overlapping booleans, sketch-to-extrude flows, etc. Returns empty if no snippet scores above the relevance floor — proceed without cookbook help in that case.

• lookup_diagnosticsFree

  Use this when you need the kernelCAD 26-code diagnostic catalogue with hint templates. Tiny one-shot call; useful for an agent that wants to pre-populate retry strategies. Hints are also inline on every emitted diagnostic — this tool just gives you the canonical list up front.

• mesh_summaryFree

  Mesh a kernelCAD .kcad.ts source server-side and return a COMPACT geometry summary — overall bounds plus, per feature, its id, kind, triangle count, and bounding box. Use this to INSPECT a model's geometry without a viewer: confirm a part is the size/shape you expect, see how many triangles each feature contributes, or check that every feature produced geometry. This runs the full server-side OCCT pipeline (the same one the Studio renderer uses), so it evaluates modern sources (assembly, path, .material, …) that the legacy client worker cannot. INPUT: `source` (required) the .kcad.ts script text; `fileName` (optional) a label for diagnostics; `params` (optional) a map of parameter-name → number overrides applied before meshing (stateless slider recompute). OUTPUT: { ok, bounds, featureCount, features: [{ id, kind, triangleCount, bbox: { min:[x,y,z], max:[x,y,z] } }], failedFeatureIds, diagnostics }. `ok` is true when every feature meshed; `failedFeatureIds` lists features that failed to compile (and `ok` is then false). Raw vertex/index/normal arrays are NEVER returned — this is a summary only. To SEE the rendered model, call open_in_studio (includes PNG preview + viewer); use get_latest_render only for alternate views.

• mesh_to_featuresFree

  Use this when you are handed an STL, OBJ or 3MF of a mostly prismatic mechanical part (plate, bracket, spacer, flange, housing block) and need an EDITABLE kernelCAD model of it rather than a faceted lib.fromSTL import. Deterministic, measured, self-verifying: it welds and checks the mesh, segments planes and cylinders, picks the extrusion axis, slices each band and fits exact lines / arcs / circles, snaps near-round values (each snap recorded), then emits a readable .kcad.ts with named param()s — a revolve for concentric round stacks, extruded profiles otherwise, .hole()/.holes() for through, blind and counterbored bores (axial and side-drilled), .cutout() for pockets, .fillet() for constant-radius edge blends (radius measured on the sharp edge, edges grouped by radius and picked with the shortest exact edge query), boolean subtractions for what no drilling feature can reach. It then EVALUATES that script and compares it with the mesh: volume IoU (column ray casting) and symmetric surface deviation (max + RMS), over up to 4 refinement passes. Returns { script, ledger, fidelity: { maxDeviationMm, rmsMm, volumeIoU, verdict: faithful | approximate | failed, thresholds }, unmatchedRegions, features, passes }. A fillet or sharp reading is kept by which measures better; variable-radius blends and chamfers are reported, not forced. The verdict is computed from the numbers — faithful needs IoU >= minIoU AND max deviation <= maxDeviationMm AND a watertight mesh AND no unmatched region. Freeform surfaces, tilted planes and side bosses are listed in unmatchedRegions (reference.mesh.freeform-region-unmatched), never silently dropped. The ledger uses fact ids equal to param names, so resolve_assumptions on the written <out>.ledger.json yields paramOverrides for set_param. Pass { out } to write the script and ledger; the mesh itself is never modified.

• open_in_studioFree

  Save/publish the current kernelCAD model AND display it in one step: persists the project, returns the interactive Studio viewer (MCP Apps / ChatGPT outputTemplate), and includes a PNG preview in the SAME tool result (image content + previewUrl when available). Use this when the user wants to SEE or share the model — do NOT call get_latest_render afterwards for the happy path; the preview is already here when previewDelivered is true. Pass the full `.kcad` source as `code` (optional if you just called evaluate_script — omitting reuses that last evaluated source). Multi-body assemblies must declare connectors + mates/joints before publish — otherwise evaluate_script fails with mechanism.orphan-part (disconnected components). Use type: 'axis' + revolute mates for shafts/hinges/gears; type: 'frame' + fastened for rigid mounts; or arm.revolute/.prismatic/.ball/.fixed. Connector types are only frame|axis|planar|ball. Pass `slug` from a previous call to update the same project in place; omit `slug` only for a new separate model. Status fields: ok=true means publish succeeded (under CDN, meshStatus ready/building; ok=false + meshStatus=failed means hard mesh persist failure — do not claim the viewer is ready). previewDelivered=true means this result carries a displayable PNG — only then may you tell the user a preview was shown. meshStatus mirrors get_project (ready|building|failed|missing). Under CDN, open_in_studio waits up to ~20s (OPEN_IN_STUDIO_MESH_SYNC_BUDGET_MS) for the revision mesh before returning; heavier publishes usually land meshStatus=ready. If still meshStatus=building + meshReady=false: TRANSIENT — meshUrl is the expected CDN pin; embed retries 404s. Poll get_project({slug}) until ready, or re-call open_in_studio with same code+slug — never treat building as permanent failure/404. ALWAYS pass `code` when you have it (avoid no_code_to_reuse); evaluate_script reuse is a fallback. Paint phases: projectSaved / meshReady / previewDelivered are set here; viewerPainted is ONLY true after widget ack (model context / widgetState) — never claim paint from this tool alone. Do NOT call get_model_mesh or get_latest_render for interactive paint. Pass include_preview:false to skip the rasterizer (save + viewer URLs only). Trigger phrases: "open it in Studio", "let me see it", "show me the model"; also call after you finish a build and after each meaningful revision while iterating. ORGANIC/CAR SUCCESS GATE: for final likeness claims pass likeness_profile:"automotive" (and body_bbox/wheels/still_verdicts, or a prior verify body-likeness pass for this code). If the gate fails, ok:false with DX reference.likeness.publish-blocked|gate-required — do not claim success. Omit likeness_profile for WIP previews only.

• project_curveFree

  Use this when you need to wrap a 2D closed curve onto a 3D face. Insert a `<shape>.projectCurve({ source, face, scaleMode? })` chained call into a kernelCAD script. The `source` is the structured `{ kind: "sketchCommands", commands: [...] }` wire format the runtime API accepts. Wraps the curve onto the face along the face normal; pair with `.extrude(d)` / `.cut(...)` for raised or engraved logos on curved bodies. Open-wire projection (`asEdge: true`) is not implemented and is rejected at edit time. Side-effect-free; returns modified code plus diagnostics.

• queryFree

  Use this when you need to resolve or inspect topology against a script's lowered geometry. Selected by `mode` (default 'evaluate'): - 'evaluate' — inspect a Query (@kc[...] ref, @kcq[...] DSL, or { ast }); returns matched entities. Pass expect:'unique' to assert exactly-one. - 'resolve' — resolve a single @kc[...] / @kcq[...] ref to one entity ({ ref }). - 'lineage' — walk the HistoryMap for a named face ref ({ feature_id, ref }). All params except `mode` are forwarded verbatim.

• remove_featurewrite actionFree

  Use this when you need to remove a feature line from a script. Remove a single line from a kernelCAD script identified by a substring match. Returns the modified code plus diagnostics from re-evaluating. Refuses to remove the line containing the return statement. Side-effect-free.

• render_previewFree

  Use this when you need to LOOK at a kernelCAD model — render its script to deterministic PNG views for visual self-check (the visual half of the evaluate → render → inspect → fix loop), with NO studio or dev server required. Pass { code } (inline source) or { file } (a .kcad.ts path), exactly one. Renders the canonical engineering views (front, right, top, iso — pass { views } for a subset, e.g. ["iso"] for fastest iteration) plus an optional { pose: "<az>,<el>" } arbitrary camera angle (degrees; az=0,el=0 is front, +az rotates CCW around +Z, +el lifts the camera). NO STUDIO / DEV-SERVER REQUIRED: a prebuilt static player (dist/headless-player) is served from an ephemeral local port automatically; a running studio dev server is used as fallback, and { base_url } forces one. The only environment dependency is playwright chromium (npx playwright install chromium). Pass { focus } or { hide } (arrays of feature ids or assembly part names, mutually exclusive) to isolate parts — same semantics as `kernelcad render --focus/--hide`. Pass { section: { axis, position, flip? } } to cut a cross-section and inspect INTERIOR geometry (wall thickness, internal pockets, whether a bore runs through) rather than only the outer shell. Pass { explode: { factor, mode? } } to pull a multi-part assembly apart (mode: "mate-axis" default, or "radial") using the same mesher as `kernelcad render --explode` — requires assembly.model()/solvedModel(). PNGs are written to { out_dir } (default: a fresh temp session directory) and returned as absolute paths with per-view camera descriptions (kernelCAD is Z-up). Mechanism truth runs first, same protocol as `kernelcad render`: a broken mechanism still renders but every tile is watermarked MECHANISM BROKEN (KERNELCAD_RENDER_STRICT=1 refuses instead); read { mechanism, mechanism_failure_codes }. The probe runs full BREP interference sweeps and can dominate latency on large assemblies — pass { no_mechanism_check: true } for fast iteration (the preview then reports mechanism: "unverified"; ignored under strict mode). Pass { overlay: 'zebra' | 'curvature' | 'continuity' } for a surface-quality visualisation (zebra stripes from vertex normals, curvature as vertex colours, continuity edges coloured by G0/G1/G2/broken) — numbers come from inspect({ of: 'continuity' | 'curvature' }); the overlay is the picture. Returns { ok, images: [{ name, path, description }], out_dir, bounds, mechanism, render_source, render_ms, diagnostics }. PATHS ARE LOCAL to the machine running the MCP server — local stdio clients read them directly; hosted/remote clients should use open_in_studio instead.

• repair_scriptFree

  Use this when evaluate_script reported an error and you want the fix applied rather than described. Takes the candidates why_did_this_fail derives for a diagnostic, applies them one at a time, re-evaluates after each, and keeps the first that clears the diagnostic without introducing new errors. Never edits outside the repair region (failing feature statement + its input statements + the param() lines it reads) — an out-of-region patch is refused with tool.repair.out-of-region. Returns the repaired source in `new_code` (the caller persists it), a unified `diff`, and before/after health maps. Pass { file? | code?, diagnostic?: '<id>'|'first-error', strategy?: 'apply-first'|'try-all'|'dry-run', max_attempts?: number }.

• resolve_assumptionsFree

  Use this when you need to confirm or override the open facts in an assumption ledger from trace_from_image (missing scale, inferred/assumed values) before committing geometry built from a reference photo. Reads the persisted `<model>.ledger.json` at `ledgerPath`, applies each resolution — `{ id, confirm: true }` to accept a fact as-is, or `{ id, value }` to override it — rewrites the ledger file, and returns the updated ledger plus `paramOverrides` (factId -> value) to feed straight into `set_param`. Pair with the `kernelcad-from-reference` skill.

• review_cadFree

  Use this when you need to review a mechanism for fitness and repair mode. Run the deterministic CAD review loop: evaluate the script, validate the assembly/mate graph, check mate connectors touch modeled material, sample declared mate limits, optionally check interferences at sampled poses, report connector workspace bounds, and return a mechanism fitness verdict for agent self-review. Fitness includes repairMode: none, local-fix, parameter-tune, or topology-redesign.

• review_paint_peek_latestFree

  Return the newest brush-painted review packet from a Studio session. After sharing a /p/<slug> link, the user can open it in the browser and paint marks over the 3D viewport to give visual feedback. Call this tool with the `slug` from that link to see the strokes — screenshot + mask + struck part names plus an optional one-line note and intent tags (e.g. "too thick", "missing", "wrong angle") describing WHAT is wrong — and act on the feedback. The slug is the capability: no OAuth required when passing `slug`; private projects require the owner to be signed in. Omit `slug` to fetch your own latest packet from your signed-in account (requires OAuth). By default returns short-lived signed Storage URLs for the screenshot + mask + meta.json plus the struck part names — small and context-friendly. Pass `paths_only: false` to also base64-inline the PNGs for clients that cannot fetch the signed URLs over HTTP.

• run_feawrite actionFree

  Use this when you need to know whether a part will hold a load. Runs the linear-static structural study a script declares with `shape.feaStudy({ material, fixed, loads, meshSize?, minSafetyFactor? })`: meshes the solid with quadratic tetrahedra, solves it with CalculiX, and returns evidence — peak von Mises stress (MPa), peak displacement (mm), the minimum safety factor against the material yield, per-region hot spots named by @kc[...] face ref, mesh-quality trust flags, an equilibrium residual, and stress-heatmap PNG paths. Requires the external solver toolchain (CalculiX `ccx` plus the gmsh Python module). When it is absent the call fails with `fea.solver.unavailable` and the exact install command — never a silent pass. Pass { file | code }, optional `study` (defaults to the last declared study), `output_dir` (keeps the .inp/.frd deck for reproduction), `mesh_size` (mm, overrides the study for this run), and `heatmaps: false` for a fast numbers-only run.

• send_to_printerwrite actionFree

  Use this when you need to upload a .gcode file (e.g. written by export with target: "model", format: "gcode") to a real network printer and, by default, start the print. protocol: 'octoprint' (POST /api/files/local with an X-Api-Key), 'moonraker' (Klipper's POST /server/files/upload), or 'bambu-lan' (Bambu Lab LAN-mode: FTPS implicit-TLS upload on port 990 as user 'bblp' with the printer's LAN access code, then an MQTT print-start command on port 8883 — requires access_code and, unless start_print is false, serial). Pass { dry_run: true } to validate connectivity/authentication only, without uploading or starting a print. Never logs or echoes api_key/access_code.

• set_paramFree

  Use this when you need to edit a param() default value in a kernelCAD script. Returns the modified code as text plus diagnostics from re-evaluating the result. Caller persists the new code via standard file-write tools (this tool has no side effects).

• set_scene_returnFree

  Use this when you need to set how the script returns its assembly. Replace the final top-level return statement with `return <assembly>.model();` or `return <assembly>.solvedModel(poses, options?);`. Use solvedModel for mate-authored mechanisms so FK and validation run. Returns modified source plus diagnostics from re-evaluation.

• solve_matesFree

  Use this when you need to solve the mate graph and get part poses. Run the v0.6 mate-graph solver on the active assembly. Returns { status, poses, iterations? } where each pose is a serialized Transform ({ translation, rotateAxis, rotateDeg }). Optional poses overrides mate pose values by mate name.

• solve_sketchFree

  Use this when you need to solve a 2D sketch constraint set. Solve a 2D sketch constraint set. Side-effect-free: pass { entities, constraints } and receive solved entities plus the original constraints. Entities are POINT, LINE, and CIRCLE records; constraints use the kernelCAD constraint vocabulary.

• sweep_toleranceFree

  Use this when you need to check whether a mechanism stays buildable across a tolerance/dimension range, not just at one nominal value. Declares one or more param() names with a { values: [...] } list or a { min, max, steps } range, re-evaluates the script once per cartesian-product combination (capped at 64 combos — exceeding it truncates to the first 64 and emits kinematic.sweep-tolerance.combo-cap-exceeded), and runs the standard gates on each combo: interference, mounting-hole diameter agreement, and joint-axis binding (all three, default on); reachability only when gates.reachable names a tip_link + target. Returns the pass/fail envelope table (one row per combo) plus firstFailure per gate — the fastest way to find the first param value at which a design breaks.

• trace_from_imageFree

  Use this when you need to trace features from a reference photo into waypoints. Trace pixel-space features from a reference photo into normalized [0..1] waypoints the agent can map to mm via a known scale anchor and feed to path().spline / path().nurbsSegment. Three backends are dispatched behind the scenes: `opencv` (deterministic; uniform-bg silhouette only), `vision-llm` (Claude vision; named points/cluttered backgrounds; caller-supplied ANTHROPIC_API_KEY), and `hybrid` (opencv silhouette + LLM-labeled named points). Default backend is `auto` — the tool picks based on the image's corner-color stddev. Accuracy honesty: opencv contour is geometrically exact; vision-LLM is typically 5–10% off on dense landmarks. Per-feature `confidence` is reported. Caller pays for any vision-LLM API spend via their own ANTHROPIC_API_KEY. Pair with the `kernelcad-trace-from-image` skill for the conversion-to-mm pipeline.

• verifyFree

  Use this when you need to check a design against a rule set. One verifier, selected by `check`: - 'assembly' — mate-aware assembly validator on the active session (run evaluate_script first). - 'urdf' — structural validity of a .urdf file ({ urdf_path }). - 'dfm' — print-readiness gates declared by dfmSpec() ({ file | code }). - 'dfm-preflight' — sheet-metal flat pattern vs a job-shop's ordering rules ({ vendor, material, thicknessIn|thicknessMm, ... }). - 'swept-collision' — sweep declared joint range(s) and report colliding poses. - 'reachable' — inverse-kinematics reachability for an end-effector ({ tip_link, target_position, ... }). - 'mounting-holes' — fastened mates expose matching hole diameters on both sides. - 'load-capacity' — closed-form Euler-Bernoulli beam stress / safety-factor check ({ loads, materials, ... }). - 'static-hold' — gravitational holding torque/force at a sampled pose grid vs each actuated joint's declared actuator capacity ({ joint?, pose?, gravity?, min_torque_margin_pct?, range_samples? }). - 'body-likeness' — publish gate for organic/car bodies: cheap AABB↔wheel checks plus required agent still verdicts (side-body-over-wheels, side-cabin-aft, rear-haunch, ortho-proportions-vs-reference). Pass { body_bbox | code/file+body_feature_id, wheels?, cabin_bbox?, still_verdicts?, require_stills? }. Full CV silhouette matching is NOT implemented — agents must inspect ortho PNGs/Studio and supply still_verdicts before claiming success. All params except `check` are check-specific and forwarded verbatim; each check fails closed on its own missing required params.

• why_did_this_failFree

  Use this when you need to trace why a feature failed. Walk the upstream chain of a failing feature. Returns the diagnostics of the requested feature plus the diagnostics of every upstream feature in topological order (the requested feature is the last entry). Per-code hints are inline on every diagnostic — call lookup_diagnostics for the full catalogue. Pass { file?, code?, feature_id? }.

• Code scan1 source files scanned25/25
• Live reliabilityremote reachable in 2143ms17/20
• Tool poisoning54 tool descriptions checked13/15
• Auth qualityopen endpoint exposes 3 write-action tools with no auth3/15
• Maintenancelast push 2 days ago15/15
• Maintainer identitynamespace and repository owner differ; GitHub account older than a year5/10

Kernelcad: common questions

Is Kernelcad MCP server safe?

Mostly: it is graded B (78/100). Read the Kernelcad safety report

How do I install Kernelcad?

It runs remotely at mcp.kernelcad.com. Add it to Claude Code, Claude Desktop or Cursor with the snippets above, or call it through the mcp.market gateway without installing anything.

Does Kernelcad need an API key?

Not as far as the registry entry and our scan can tell: no credentials are declared or required.

Is Kernelcad maintained?

The last commit was 3 days ago (2026-09-25). The latest release is v0.11.2.

Is Kernelcad up?

100% of our last 28 checks got an answer. We check remote servers about four times a day.

What can I use instead of Kernelcad?

Servers from other publishers that do the same job: Basic Memory MCP server, Agent-Native Chat MCP server and Agent Recall MCP server. Compare all Kernelcad alternatives.