aseprite-mcp

aseprite_onion_preview

Render a frame with previous frame ghosted red and next frame ghosted cyan to check motion arcs for swings, walks, or bounces.

Instructions

Render a frame with the previous frame ghosted red and the next frame ghosted cyan. This is how animators check that motion reads correctly between frames - use it to verify the arc of a swing, a walk, or a bounce.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "frame": "<frame>"
    },
    "name": "aseprite_onion_preview"
  }
}

Input Schema

Name	Required	Description
`frame`	Yes	Zero-based frame index (omit for the first frame).
`scale`	No
`document`	No	Document to act on: a short name inside the art folder ("hero"), a relative path, or an absolute .aseprite path. Omit to use the active document.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Sep 27, 2026

TDQS

A4/5.0

Behavior3/5

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

With no annotations, the description carries the full burden. It usefully discloses what the render looks like (red/cyan ghosting, adjacent-frame comparison), but says nothing about whether this is a read-only operation, whether it returns an image or writes a file, or any side effects—leaving real behavioral gaps for a tool with zero annotation coverage.

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?

Two sentences, zero waste, and the concrete rendering behavior is front-loaded before the use case. Every clause earns its place.

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?

For a simple 3-parameter read-style tool with no output schema, the description conveys enough to invoke it correctly. The only shortfall is not clarifying the output medium (returned image vs. saved file), which matters in a family of view/export tools.

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%: 'frame' and 'document' are documented in the schema, 'scale' is not, and the description adds no parameter-level detail (e.g., what scale does to output). Baseline 3 is appropriate since the schema does most of the work.

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?

States a specific verb+resource ('Render a frame') and immediately specifies the distinct visual output: previous frame ghosted red, next frame ghosted cyan. This is clearly distinguishable from siblings like aseprite_view, aseprite_export_png, or aseprite_inspect_pixels.

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

Usage Guidelines4/5

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

Explicitly gives the use case ('use it to verify the arc of a swing, a walk, or a bounce'), which tells the agent when this diagnostic is appropriate. It does not name an alternative tool or state exclusions, so it falls short of a 5.

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

Deploy Server