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Transform

transform

Transform pixels on a single cel by translating, flipping, rotating, scaling, outlining, or cropping to content. Supports only clean 90° rotations and integer scaling to preserve pixel art.

Instructions

Move, flip, rotate or scale pixels on ONE cel — the target layer's image on the target frame. Ops: 'translate', 'flip', 'rotate', 'scale', 'outline', 'crop_to_content'. To transform part of a cel, crop the region out with draw op 'blit' first; there is no selection-scoped transform. Rotation is only clean at 90° multiples — arbitrary angles destroy pixel art, so anything else needs allowLossy. Scaling is nearest-neighbour and integer-only for the same reason.

Input Schema

TableJSON Schema

Name	Required	Description
`dx`	No
`dy`	No
`op`	Yes
`axis`	No	For 'flip'.
`angle`	No	Degrees, clockwise. For 'rotate'.
`color`	No	Outline colour, for 'outline'.
`frame`	No	1-based frame number. Omit to use the active frame.
`layer`	No	Layer name. Omit to use the active layer.
`factor`	No	For 'scale'.
`sprite`	No	Which sprite: its id as '#7' (what every result reports back, and the only unambiguous form — two unsaved documents are both called 'Sprite'), its filename, or its display name. Omit to use the sprite Aseprite has focused.
`thickness`	No
`allowLossy`	No	Permit a non-90° rotation or non-integer scale. Ask the user first.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`op`	Yes
`bounds`	No
`sprite`	Yes
`pixelsChanged`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv0.1.6Sep 9, 2026

removedInput schema / properties / scope

Removed value: -{
-  "default": "selection",
-  "description": "What the transform applies to. 'selection' falls back to the cel when nothing is selected.",
-  "enum": [
-    "selection",
-    "cel",
-    "layer",
-    "sprite"
-  ],
-  "type": "string"
-}

changedInput schema / properties / sprite / description

Previous value: -"Sprite filename or id. Omit to use the sprite Aseprite has focused."New value: +"Which sprite: its id as '#7' (what every result reports back, and the only unambiguous form — two unsaved documents are both called 'Sprite'), its filename, or its display name. Omit to use the sprite Aseprite has focused."

removedOutput schema / properties / scope

Removed value: -{
-  "type": "string"
-}

changedOutput schema / required

Previous value: -[
-  "sprite",
-  "op",
-  "scope",
-  "pixelsChanged"
-]New value: +[
+  "sprite",
+  "op",
+  "pixelsChanged"
+]

First observedv0.1.0Sep 8, 2026

TDQS

A4.6/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only say readOnlyHint=false, destructiveHint=false — they carry no safety or behavioral detail. The description carries the full burden and discloses rich traits: arbitrary-angle rotation destroys pixel art (requires allowLossy), scaling is nearest-neighbour and integer-only, and there is no selection-scoped transform. These go well beyond what annotations provide and are accurate to the mutation semantics. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single dense paragraph that front-loads the core purpose and ops, then packs the lossiness constraints, the selection limitation, and the alternative tool into compact, high-information sentences. Every sentence earns its place with zero filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Complex 12-parameter mutation tool with an output schema present, so return values need no explanation. The description covers ops, selection scoping, lossy behavior, and the draw/blit alternative. Minor gap: it doesn't spell out required companion params per op (e.g., axis for flip, factor for scale), which is left to the schema — acceptable but not exhaustive.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is ~67%, so the schema already documents op, axis, angle, color, frame, layer, factor, sprite, and allowLossy individually. The description adds behavioral meaning tied to parameters (rotation lossiness → angle/allowLossy, integer scaling → factor) but does not enumerate parameters directly. It adds some value without fully compensating for the undocumented dx/dy/thickness.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb+resource ('Move, flip, rotate or scale pixels on ONE cel') and enumerates the six ops. It clearly delimits scope to a single cel (target layer's image on the target frame), which distinguishes it from sibling tools like draw, read_pixels, and cel.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly names the alternative and the condition that selects it: 'To transform part of a cel, crop the region out with draw op 'blit' first; there is no selection-scoped transform.' This is direct routing to a sibling tool under a stated condition, which fully satisfies the when/when-not guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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