Adjust the opacity of a specific cel in an Aseprite file by specifying its layer, frame, and a value from 0 (transparent) to 255 (opaque).
Set the opacity of a single cel (0-255).
Args: filename: Aseprite file to modify layer_name: Layer containing the cel frame_index: Frame index starting at 1 opacity: Opacity 0 (transparent) to 255 (opaque)
| Name | Required | Description | Default |
|---|---|---|---|
| opacity | Yes | ||
| filename | Yes | ||
| layer_name | Yes | ||
| frame_index | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description carries the full burden. It confirms a mutation (setting opacity) but discloses no side effects, idempotency, error conditions (e.g., if cel doesn't exist), or permissions needed. The agent lacks behavioral context beyond the basic operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is very concise, with a brief sentence and a list of arguments. It is easy to scan and front-loaded. However, it could be more structured (e.g., separate parameter descriptions).
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple setter tool with no output schema and no annotations, the description is minimally adequate. It explains the core action and parameter meanings but lacks context about return values, error handling, or prerequisites. The tool's simplicity reduces the need for extensive completeness, but gaps remain.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema has 0% description coverage, so the description must add meaning. It clarifies opacity range (0-255) and frame_index starting at 1, but filename and layer_name are not elaborated. This adds some value but not full parameter context.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states it sets the opacity of a single cel, which is a specific verb-resource combination. The tool name 'set_cel_opacity' is descriptive, and the sibling tools include tween variants, so this tool's purpose is distinct.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies usage for setting opacity on a frame/layer combination, but does not explicitly state when to use this vs. alternatives like tween_cel_opacity_eased or set_cel_position. No when-not guidance is provided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.