mask_stroke

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

With no annotations, the description carries the full behavioral burden. It does disclose meaningful traits: mode semantics, that points are in document pixels, that it works on any mask, and the side effect that a mask-less layer silently gets a new paint mask. It omits whether existing mask content is replaced or blended, how opacity/hardness affect the result, and any auth/undo considerations.

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 dense sentences with the core operation front-loaded, followed by scope and the auto-mask side effect. No filler; every clause carries information.

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?

Seven parameters, none documented in the schema and no annotations or output schema, so the description is the only source. It covers the two required parameters and mode, but leaves five optional brush/targeting parameters undocumented, which is thin for a 7-parameter paint tool.

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. It documents two of seven parameters well (mode as hide/reveal, points as [[x,y],...] in document px), but size, hardness, opacity, layer, and project are left entirely unexplained, including the units for the brush parameters.

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?

Clear specific verb+resource: 'Paint on a layer's mask', with mode hide/reveal and the polyline input format named. It distinguishes itself from set_mask/update_mask/remove_mask implicitly by being a freehand paint operation, but never explicitly contrasts with the sibling paint_stroke or the mask-management 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 parenthetical 'refine an AI cut-out' gives one concrete usage scenario, which implies when this tool is appropriate. However, there is no guidance on when to prefer update_mask/set_mask over painting, nor any exclusion or prerequisite, so usage is only implied.

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