Paint: Freehand brush stroke

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

With annotations only declaring a general mutation profile (readOnly=false, destructive=false, idempotent=false), the description adds real behavioral texture: stroke construction from pressure-carrying points, the flatten/angle calligraphy nib, jitter wobble, low-hardness spray, and the preview parameter's image-reply behavior. It also reassures that layers/filters/undo apply uniformly, implying recoverability. It does not cover failure modes or the effect of large point counts.

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?

Two tight paragraphs, front-loaded with the core mental model ('Mouse-drag feel') before parameter effects and targeting. Every sentence carries information, though the interleaving of parameter tips is slightly scattered rather than structured.

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 15-parameter mutating draw tool with no output schema, the description covers targeting, coordinate/pressure format, stylistic parameter effects, preview return behavior, and shared layer/filter/undo semantics. Only minor gaps remain, such as seed/opacity/spacing/blend usage, which the schema itself documents.

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 coverage is 67% across 15 parameters, so the schema handles much of the load, but the description adds interpretation the schema lacks: the third point value as pressure 0..1, and the combined semantics of flatten+angle (nib), jitter (wobble), and hardness (spray). This is meaningful value beyond field-level descriptions.

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 names a specific verb+resource ('soft stamps along a polyline', 'Mouse-drag feel') and titles the tool as a freehand brush stroke, which an agent can distinguish from vector siblings like paint_line or paint_path. It also anchors the tool by naming paint_canvas as the source of the canvas. It stops short of explicitly contrasting when to pick this over paint_stamp or paint_path.

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?

It states the prerequisite that the canvas is 'created with paint_canvas' and that a layer index is optional, and notes that layers/filters/undo behave the same across drawing tools. There is no explicit when-to-use vs when-not guidance or direct alternative comparison among the many paint_* siblings.

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