Draw a straight line between two points on a pixel-art canvas by entering start and end coordinates and a hex color, ensuring consistent style for 2D RPG game assets.
Draw a line between two points using Bresenham algorithm.
| Name | Required | Description | Default |
|---|---|---|---|
| x0 | Yes | Start X coordinate | |
| x1 | Yes | End X coordinate | |
| y0 | Yes | Start Y coordinate | |
| y1 | Yes | End Y coordinate | |
| color | Yes | Line color as hex string | |
| session_id | Yes | Canvas session ID |
Changes observed during successful MCP inspections.
v0.3.0Does 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 mentions the Bresenham algorithm, which hints at integer rasterization, but does not disclose state mutation, coordinate bounds, behavior with invalid points, or whether drawing overrides existing pixels. For a mutation tool, this 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, concise sentence that front-loads the action and avoids irrelevant detail. Every word contributes to understanding what the tool does.
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?
The tool is fairly simple and the schema fully documents its six parameters. However, with no annotations or output schema, and no mention of behavioral constraints like coordinate handling or session assumptions, the description is only minimally complete for correct invocation.
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 100%, so the parameter descriptions already document each coordinate, color, and session ID. The description adds no extra parameter semantics beyond the algorithm hint; this aligns with the baseline score for a well-covered schema.
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 the operation: drawing a line between two points on a canvas, and identifies the algorithm (Bresenham). This distinguishes it from sibling tools like art.canvas.draw_circle, art.canvas.draw_rect, and art.canvas.set_pixel without requiring schema inspection.
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 intended use is implicit: use this when a line needs to be drawn. However, the description gives no explicit guidance about when to choose this over alternative drawing tools or any exclusions or prerequisites such as session initialization.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.