set_pixels

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

With no annotations, the description carries the full burden and delivers real behavioral facts: operations are atomic in a single undo step, and it returns modified count, bounding box, and optional preview. It omits any permission/auth requirements or constraints like the layerName/layerIndex mutual exclusivity, which is a minor 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?

Two tight sentences with the most important routing signal ('PRIMARY DRAWING TOOL') front-loaded, followed by behavioral and return-value facts. No filler or redundancy.

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?

No output schema exists, and the description compensates by naming the return payload (modified count, bounding box, optional preview). Atomicity and batch scope are covered for a 6-parameter mutation tool, leaving only permission/layer-targeting caveats unaddressed.

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 every parameter (pixels, layerName, layerIndex, frameNumber, previewScale, returnPreview) is already documented in the schema. The description adds no parameter-level syntax or format detail beyond what the schema provides, so the baseline 3 applies.

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?

States a specific verb (Paints) and resource (pixels) with clear scope: batched tens-to-thousands in one call. 'PRIMARY DRAWING TOOL' signals it is the default over per-pixel siblings like set_pixel, though it never names the alternative directly.

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 'PRIMARY DRAWING TOOL' label implies this is the preferred path for painting, which is implicit routing guidance. It gives no explicit when-not conditions or named alternatives (e.g. set_pixel for single pixels, draw_line/draw_rectangle for shapes).

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