lentera-aseprite-mcp

run_lua_script

Execute custom Lua scripts in Aseprite to automate pixel art tasks beyond standard tools, using the full Lua API.

Instructions

Execute arbitrary Lua code inside Aseprite. Use for operations not covered by other tools.

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": {
      "script": "<script>"
    },
    "name": "run_lua_script"
  }
}

Input Schema

Name	Required	Description	Default
`script`	Yes	Lua code to execute. Has access to full Aseprite Lua API.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 14, 2026

TDQS

A4.1/5.0

Behavior3/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions 'arbitrary Lua code' and 'full Aseprite Lua API', which implies broad capabilities and potential destructiveness, but it does not explicitly warn about side effects, error handling, or sandboxing. This is only a moderate disclosure.

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?

The description is two sentences long with no wasted words. It front-loads the primary action and then adds the crucial usage guideline. Every sentence earns its place and the structure is highly efficient.

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

Completeness3/5

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

The tool is a generic code execution tool, and while the description gives a clear use case, it lacks context about what the script can actually do (e.g., access to active sprite, file system, return values). Given there is no output schema and no annotations, the description could be more complete to guide the agent on the tool's capabilities and potential side effects.

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?

The input schema already describes the 'script' parameter with 100% coverage, including that it has access to the full Aseprite Lua API. The description does not add additional meaning beyond the schema, so the baseline of 3 is appropriate.

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 clearly states 'Execute arbitrary Lua code inside Aseprite', which is a specific verb (execute) and resource (Lua code inside Aseprite). It also distinguishes itself from siblings by positioning as the fallback for operations not covered by other tools, making its purpose unmistakable.

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?

The description explicitly provides usage guidance: 'Use for operations not covered by other tools.' This tells the agent when to use this tool and implies that for other operations, dedicated sibling tools should be used instead, which is an explicit alternative.

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