kernelcad

Trace Outline from Image

trace_from_image

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 (vision model; named points/cluttered backgrounds; needs ANTHROPIC_API_KEY or an OpenAI-compatible vision endpoint configured on the server), 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. Vision-LLM spend is billed to whoever configured the vision model. Pair with the kernelcad-trace-from-image skill for the conversion-to-mm pipeline. Hosted: give the file as an https:// URL, a data: URI (base64, max 25 MB) or "asset:" from request_upload (when the file is on the user's device).

Input Schema

TableJSON Schema

Name	Required	Description
`hint`	No	Optional free-text hint forwarded to vision-LLM backends (e.g. "a pair of eyewear; trace the upper brow only").
`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.
`priors`	No	Caller-supplied category-norm defaults (e.g. wall thickness) recorded verbatim as `assumed` ledger facts.
`backend`	No	Force a specific backend; default `auto` routes by corner-color stddev.
`features`	No	Features to trace. Defaults to a single { label: "silhouette", kind: "silhouette" } when omitted.
`imageUrl`	Yes	URL or path to the reference image. Supports file://, http(s)://, data:image/...;base64,..., or a bare filesystem path. Hosted server: pass an https:// URL, a data: URI, or "asset:<id>" from request_upload — not a path on your machine.
`validate`	No	Assumption-ledger strictness. `warn` (default) never blocks. `error` fails the call when any `missing` ledger fact (e.g. scale) is still open.
`scaleAnchor`	No	Pixel-to-real-world scale anchor: two measured points on the image. Absent -> the returned ledger's `scale` fact is `missing`.
`maxWaypointsPerFeature`	No	Cap on waypoints per feature. Defaults to 12 (suitable for medium-inflection outlines).

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"
-  },
-  "features": {
-    "description": "Traced features with normalized [0..1] waypoints + confidence.",
-    "items": {
-      "additionalProperties": true,
-      "type": "object"
-    },
-    "type": "array"
-  },
-  "imageDims": {
-    "description": "Pixel dimensions [width, height] of the source image.",
-    "items": {
-      "type": "number"
-    },
-    "type": "array"
-  },
-  "ledger": {
-    "additionalProperties": true,
-    "description": "Assumption ledger: { facts, scale?, unresolvedCount } classifying every fact as visible/inferred/assumed/missing.",
-    "type": "object"
-  },
-  "ok": {
-    "type": "boolean"
-  }
-}

removedOutput schema / required

Removed value: -[
-  "ok",
-  "features",
-  "imageDims",
-  "diagnostics",
-  "ledger"
-]

Changed2 schema fields changedOct 3, 2026

changedInput schema / properties / imageUrl / description

Previous value: -"URL or path to the reference image. Supports file://, http(s)://, data:image/...;base64,..., or a bare filesystem path."New value: +"URL or path to the reference image. Supports file://, http(s)://, data:image/...;base64,..., or a bare filesystem path. Hosted server: pass an https:// URL, a data: URI, or \"asset:<id>\" from request_upload — not a path on your machine."

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"
+}

Changed5 schema fields changedSep 21, 2026

addedInput schema / properties / priors

Added value: +{
+  "description": "Caller-supplied category-norm defaults (e.g. wall thickness) recorded verbatim as `assumed` ledger facts.",
+  "items": {
+    "properties": {
+      "confidence": {
+        "maximum": 1,
+        "minimum": 0,
+        "type": "number"
+      },
+      "id": {
+        "type": "string"
+      },
+      "statement": {
+        "type": "string"
+      },
+      "value": {}
+    },
+    "required": [
+      "id",
+      "statement",
+      "value",
+      "confidence"
+    ],
+    "type": "object"
+  },
+  "type": "array"
+}

addedInput schema / properties / scaleAnchor

Added value: +{
+  "description": "Pixel-to-real-world scale anchor: two measured points on the image. Absent -> the returned ledger's `scale` fact is `missing`.",
+  "properties": {
+    "pixelDistance": {
+      "description": "Distance in pixels between the two measured points.",
+      "type": "number"
+    },
+    "realDistance": {
+      "description": "The same distance in real-world units.",
+      "type": "number"
+    },
+    "unit": {
+      "enum": [
+        "mm",
+        "cm",
+        "in"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "pixelDistance",
+    "realDistance",
+    "unit"
+  ],
+  "type": "object"
+}

addedInput schema / properties / validate

Added value: +{
+  "description": "Assumption-ledger strictness. `warn` (default) never blocks. `error` fails the call when any `missing` ledger fact (e.g. scale) is still open.",
+  "enum": [
+    "warn",
+    "error"
+  ],
+  "type": "string"
+}

addedOutput schema / properties / ledger

Added value: +{
+  "additionalProperties": true,
+  "description": "Assumption ledger: { facts, scale?, unresolvedCount } classifying every fact as visible/inferred/assumed/missing.",
+  "type": "object"
+}

changedOutput schema / required

Previous value: -[
-  "ok",
-  "features",
-  "imageDims",
-  "diagnostics"
-]New value: +[
+  "ok",
+  "features",
+  "imageDims",
+  "diagnostics",
+  "ledger"
+]

AddedJun 17, 2026
RemovedJun 16, 2026

Changed1 schema field changedJun 15, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "properties": {
+    "diagnostics": {
+      "items": {
+        "additionalProperties": true,
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "features": {
+      "description": "Traced features with normalized [0..1] waypoints + confidence.",
+      "items": {
+        "additionalProperties": true,
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "imageDims": {
+      "description": "Pixel dimensions [width, height] of the source image.",
+      "items": {
+        "type": "number"
+      },
+      "type": "array"
+    },
+    "ok": {
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "ok",
+    "features",
+    "imageDims",
+    "diagnostics"
+  ],
+  "type": "object"
+}

First observedMay 25, 2026

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