Read the exact RGBA color of a pixel from a specific cel by providing filename, x, and y coordinates. Retrieve precise pixel data for verification or color sampling in your Aseprite project.
Read one RGBA pixel from a cel.
| Name | Required | Description | Default |
|---|---|---|---|
| x | Yes | ||
| y | Yes | ||
| filename | Yes | ||
| layer_name | No | ||
| frame_index | No |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the operation is a read, but does not disclose what happens if coordinates are out of bounds, whether the cel must be visible, how layer_name and frame_index interact, or whether the returned pixel is pre- or post-composite. For a read tool, the lack of error/edge-case behavior is a notable gap.
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 a single, efficient sentence that front-loads the core action and output format. Every word earns its place; there is no fluff or repetition of schema details.
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 tool with 5 parameters, no annotations, and no output schema, the description is too thin. It does not explain coordinate semantics, layer/frame defaults, error behavior, or the return value structure beyond 'RGBA'. An agent would need to open the schema and guess at conventions, which is risky for a pixel-level read operation.
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?
Schema description coverage is 0%, so the description must compensate for the parameters. It does not explain what 'cel' means in this context, how x/y are measured (pixel coordinates relative to the cel or canvas), what layer_name defaults to, or what frame_index=1 means (1-based indexing is unusual and should be called out). The description adds almost no parameter-level meaning beyond the schema's names and types.
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 'Read one RGBA pixel from a cel' clearly states the verb (read), the resource (a pixel from a cel), and the output format (RGBA). It is concise and unambiguous. It doesn't explicitly distinguish from sibling tools like get_pixels_rect or get_composite_pixel, but the singular pixel scope is clear enough to differentiate it from bulk read tools.
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 provides no guidance on when to use this tool versus alternatives like get_pixels_rect, get_composite_pixel, or get_color_stats. There is no mention of prerequisites (e.g., cel must exist, layer/frame context) or exclusions. The agent must infer usage from the name and schema alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.