lentera-aseprite-mcp

draw_rect

Draw rectangles on the canvas with specified position, width, height, color, and optional fill.

Instructions

Draw a rectangle (outline or filled) on the canvas.

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": {
      "color": "<color>"
    },
    "name": "draw_rect"
  }
}

Input Schema

Name	Required	Description
`x`	No
`y`	No
`color`	Yes	{r,g,b,a}
`frame`	No
`layer`	No
`width`	No
`filled`	No	Fill the rectangle (default: false = outline)
`height`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 14, 2026

TDQS

C2.7/5.0

Behavior2/5

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

With no annotations, the description carries the full burden of behavioral disclosure. It mentions the outline/filled option, but omits key behavioral traits such as interaction with the active layer/frame, coordinate system, whether it overwrites or composites pixels, and any return values. Significant gaps remain.

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

Conciseness4/5

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

The description is a single, focused sentence with no waste. It is front-loaded with the core action and includes a key option. However, it is under-specified overall, so not a 5.

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

Completeness2/5

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

Given the tool's complexity (8 parameters, nested color object, no output schema, no annotations), the description is too thin. It lacks essential context about layer/frame targeting, parameter defaults, and return behavior, making it inadequate for reliable invocation.

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

Parameters2/5

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

Schema description coverage is only 25% (only color and filled have descriptions). The description adds meaning to 'filled' (outline vs filled) but fails to explain x, y, width, height, frame, or layer. Most parameters remain undocumented, and the description does not compensate for the low coverage.

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

Purpose4/5

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

The description clearly states the tool's function: drawing a rectangle on the canvas. It mentions 'outline or filled', which distinguishes it from sibling drawing tools like draw_circle or draw_ellipse. However, it does not explicitly name alternatives, so only a 4.

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

Usage Guidelines2/5

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

No guidance is provided on when to use this tool versus other drawing tools (e.g., draw_pixels, fill_area, outline). The description simply states what it does without giving context on selection criteria or alternatives.

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