kernelcad

Evaluate CAD Script

evaluate_script

Read-only

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 — a mechanism (any mate, joint, transmission or .solvedModel()) needs every part linked by connectors + mates/joints (axis+revolute for shafts/hinges/gears; frame+fastened for rigid; or arm.revolute/.prismatic/.ball/.fixed). A plain multi-part assembly with no mates (base + lid, print layout) is independent bodies and passes. Pass { skipMechanismCheck: true } to opt out (e.g. a deliberately free part next to a mechanism). Every union() is checked too (no opt-out): union.disconnected (the union is several separate solids — a floating operand) and union.member-overlap (two operands that each carry their own .finish()/.material(), the same one, share > 1 mm³ — cut members to fit, e.g. a cross tube between rails is span minus two rail widths) make ok:false. Pass either { file: "" } or { code: "" }. Set { dryRun: true } for fast validation while iterating: transpile + capture + capture-light checks without building solids, 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. To show a measurement in the 3D viewer (e.g. hole spacing), declare it in the script with shape.dimension({ kind: "linear", from, to, label }); a full evaluate lists them as dimensions: [{ text, kind, source }], and a shared /p link with ?dims=1 forces them on. Hosted: lib.fromSTEP / fromSTL / fromDXF / fromSVG and referenceImage accept "asset:" (from request_upload), an https:// URL or a data: URI as the path.

Input Schema

TableJSON Schema

Name	Required	Description
`code`	No	Inline kernelCAD script source.
`file`	No	Path to a .kcad.ts script file. Hosted server: cannot read files from your machine — pass `code`, or `project:<slug>` for a saved project.
`dryRun`	No	Fast validation only: skip solid build, DFM gates, and meshing. Does not set or clear the active session.
`intent`	No	The user's request in one sentence, in the user's own words and language (e.g. 'M4 bracket for a 25 mm tube, print on Bambu A1'). Helps kernelCAD improve; leave out personal data.
`skipMechanismCheck`	No	Opt out of the default mechanism-truth gate. By default a full evaluation of an assembly-built scene runs checkMechanismTruth and returns a `mechanism` verdict (real/broken/unverified); a broken mechanism makes ok:false. Set true to skip the sweep entirely (no `mechanism` field, no cost). Ignored for dryRun and non-assembly scripts.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 11, 2026

removedOutput schema / properties

Removed value: -{
-  "diagnostics": {
-    "items": {
-      "additionalProperties": true,
-      "type": "object"
-    },
-    "type": "array"
-  },
-  "dimensions": {
-    "description": "Dimensions declared with shape.dimension(), as the viewer labels them (e.g. \"hole spacing 30\"). Omitted when the script declares none.",
-    "items": {
-      "additionalProperties": false,
-      "properties": {
-        "kind": {
-          "enum": [
-            "linear",
-            "diameter",
-            "radius",
-            "angular"
-          ],
-          "type": "string"
-        },
-        "source": {
-          "enum": [
-            "declared",
-            "auto"
-          ],
-          "type": "string"
-        },
-        "text": {
-          "type": "string"
-        }
-      },
-      "required": [
-        "text",
-        "kind",
-        "source"
-      ],
-      "type": "object"
-    },
-    "type": "array"
-  },
-  "dryRun": {
-    "description": "True when the result came from a fast dry run.",
-    "type": "boolean"
-  },
-  "featureCount": {
-    "description": "Number of features captured by the script.",
-    "type": "number"
-  },
-  "featureHealth": {
-    "description": "Per-feature health degradations — ONLY features that fell back to a passthrough (warning) or failed to lower (error). Empty when every feature is healthy. Surfaces which feature degraded even when ok is true.",
-    "items": {
-      "additionalProperties": false,
-      "properties": {
-        "featureId": {
-          "type": "string"
-        },
-        "status": {
-          "enum": [
-            "warning",
-            "error"
-          ],
-          "type": "string"
-        }
-      },
-      "required": [
-        "featureId",
-        "status"
-      ],
-      "type": "object"
-    },
-    "type": "array"
-  },
-  "mechanism": {
-    "description": "Mechanism-truth verdict for an assembly-built scene (default-on; omitted for dryRun, non-assembly, or skipMechanismCheck:true). 'broken' makes ok:false; 'unverified' keeps ok and surfaces a loud budget diagnostic.",
-    "enum": [
-      "real",
-      "broken",
-      "unverified"
-    ],
-    "type": "string"
-  },
-  "ok": {
-    "description": "Whether the script compiled and lowered cleanly.",
-    "type": "boolean"
-  },
-  "parts": {
-    "additionalProperties": true,
-    "description": "Assembly parts summary { count, names } when the scene is assembly-built.",
-    "type": "object"
-  },
-  "reviewHint": {
-    "description": "Present only when a captured assembly declares articulated (non-fastened) mates: the default mechanism check is shallow (no joint-support intents, pose-envelope overlap at declared limits, or gravity drop) — run review_cad for pose-envelope + gravity checks.",
-    "type": "string"
-  },
-  "tubes": {
-    "additionalProperties": false,
-    "description": "Tube line report. Present only when the model has tubes; the gate diagnostics are in diagnostics.",
-    "properties": {
-      "lines": {
-        "description": "One entry per tube: name, system, od, wall, bendRadius, material, cutLength (mm), bends, xyz (bend-table corner points), lra (length/rotation/angle rows), lastStraight, minStraight, minClearance { mm, to, at } (exact nearest part or tube), massKg (null without a known material or density), volumeInternalMl, pressureDropKPa (null without a declared flow).",
-        "items": {
-          "additionalProperties": true,
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "systems": {
-        "description": "One entry per named system: { system, lines, cutLength, massKg }.",
-        "items": {
-          "additionalProperties": true,
-          "type": "object"
-        },
-        "type": "array"
-      }
-    },
-    "required": [
-      "lines",
-      "systems"
-    ],
-    "type": "object"
-  }
-}

removedOutput schema / required

Removed value: -[
-  "ok",
-  "featureCount",
-  "diagnostics"
-]

Changed1 schema field changedOct 11, 2026

addedOutput schema / properties / tubes

Added value: +{
+  "additionalProperties": false,
+  "description": "Tube line report. Present only when the model has tubes; the gate diagnostics are in diagnostics.",
+  "properties": {
+    "lines": {
+      "description": "One entry per tube: name, system, od, wall, bendRadius, material, cutLength (mm), bends, xyz (bend-table corner points), lra (length/rotation/angle rows), lastStraight, minStraight, minClearance { mm, to, at } (exact nearest part or tube), massKg (null without a known material or density), volumeInternalMl, pressureDropKPa (null without a declared flow).",
+      "items": {
+        "additionalProperties": true,
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "systems": {
+      "description": "One entry per named system: { system, lines, cutLength, massKg }.",
+      "items": {
+        "additionalProperties": true,
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "lines",
+    "systems"
+  ],
+  "type": "object"
+}

Changed1 schema field changedOct 9, 2026

changedInput schema / properties / dryRun / description

Previous value: -"Fast validation only: skip OCCT lowering, DFM gates, and meshing. Does not set or clear the active session."New value: +"Fast validation only: skip solid build, DFM gates, and meshing. Does not set or clear the active session."

Changed1 schema field changedOct 5, 2026

addedOutput schema / properties / dimensions

Added value: +{
+  "description": "Dimensions declared with shape.dimension(), as the viewer labels them (e.g. \"hole spacing 30\"). Omitted when the script declares none.",
+  "items": {
+    "additionalProperties": false,
+    "properties": {
+      "kind": {
+        "enum": [
+          "linear",
+          "diameter",
+          "radius",
+          "angular"
+        ],
+        "type": "string"
+      },
+      "source": {
+        "enum": [
+          "declared",
+          "auto"
+        ],
+        "type": "string"
+      },
+      "text": {
+        "type": "string"
+      }
+    },
+    "required": [
+      "text",
+      "kind",
+      "source"
+    ],
+    "type": "object"
+  },
+  "type": "array"
+}

Changed1 schema field changedOct 3, 2026

addedInput schema / properties / intent

Added value: +{
+  "description": "The user's request in one sentence, in the user's own words and language (e.g. 'M4 bracket for a 25 mm tube, print on Bambu A1'). Helps kernelCAD improve; leave out personal data.",
+  "maxLength": 2000,
+  "type": "string"
+}

Changed1 schema field changedSep 29, 2026

addedOutput schema / properties / reviewHint

Added value: +{
+  "description": "Present only when a captured assembly declares articulated (non-fastened) mates: the default mechanism check is shallow (no joint-support intents, pose-envelope overlap at declared limits, or gravity drop) — run review_cad for pose-envelope + gravity checks.",
+  "type": "string"
+}

Changed1 schema field changedSep 28, 2026

changedInput schema / properties / file / description

Previous value: -"Path to a .kcad.ts script file."New value: +"Path to a .kcad.ts script file. Hosted server: cannot read files from your machine — pass `code`, or `project:<slug>` for a saved project."

Changed3 schema fields changedSep 21, 2026

addedInput schema / properties / skipMechanismCheck

Added value: +{
+  "description": "Opt out of the default mechanism-truth gate. By default a full evaluation of an assembly-built scene runs checkMechanismTruth and returns a `mechanism` verdict (real/broken/unverified); a broken mechanism makes ok:false. Set true to skip the sweep entirely (no `mechanism` field, no cost). Ignored for dryRun and non-assembly scripts.",
+  "type": "boolean"
+}

addedOutput schema / properties / featureHealth

Added value: +{
+  "description": "Per-feature health degradations — ONLY features that fell back to a passthrough (warning) or failed to lower (error). Empty when every feature is healthy. Surfaces which feature degraded even when ok is true.",
+  "items": {
+    "additionalProperties": false,
+    "properties": {
+      "featureId": {
+        "type": "string"
+      },
+      "status": {
+        "enum": [
+          "warning",
+          "error"
+        ],
+        "type": "string"
+      }
+    },
+    "required": [
+      "featureId",
+      "status"
+    ],
+    "type": "object"
+  },
+  "type": "array"
+}

addedOutput schema / properties / mechanism

Added value: +{
+  "description": "Mechanism-truth verdict for an assembly-built scene (default-on; omitted for dryRun, non-assembly, or skipMechanismCheck:true). 'broken' makes ok:false; 'unverified' keeps ok and surfaces a loud budget diagnostic.",
+  "enum": [
+    "real",
+    "broken",
+    "unverified"
+  ],
+  "type": "string"
+}

Changed1 schema field changedJun 15, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "properties": {
+    "diagnostics": {
+      "items": {
+        "additionalProperties": true,
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "dryRun": {
+      "description": "True when the result came from a fast dry run.",
+      "type": "boolean"
+    },
+    "featureCount": {
+      "description": "Number of features captured by the script.",
+      "type": "number"
+    },
+    "ok": {
+      "description": "Whether the script compiled and lowered cleanly.",
+      "type": "boolean"
+    },
+    "parts": {
+      "additionalProperties": true,
+      "description": "Assembly parts summary { count, names } when the scene is assembly-built.",
+      "type": "object"
+    }
+  },
+  "required": [
+    "ok",
+    "featureCount",
+    "diagnostics"
+  ],
+  "type": "object"
+}

Changed1 schema field changedJun 12, 2026

addedInput schema / properties / dryRun

Added value: +{
+  "description": "Fast validation only: skip OCCT lowering, DFM gates, and meshing. Does not set or clear the active session.",
+  "type": "boolean"
+}

First observedMay 25, 2026

TDQS

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