addLayerMask

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

With no annotations, the description carries the full behavioral burden for a mutation tool and delivers little. It does not state that a new mask is appended, how the layer is resolved, whether the operation is undoable, or what happens on invalid shape/bounds combinations; the listed attributes (mode, feather, opacity) merely repeat schema fields.

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?

A single well-front-loaded sentence with the action first and shape types as a parenthetical. It is efficient, though the shape enumeration slightly duplicates the shapeType enum already in the schema.

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 mutation tool with no annotations and no output schema, the description is thin. It omits the critical targeting question of how layerName/layerIndex/compName combine and how shapeType gates which of bounds, vertices, and tangents are actually used.

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 schema already documents all 15 parameters including defaults and enums. The description's mention of mode, feather, and opacity adds nothing beyond the schema, 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+resource ('Add a new mask to a layer') and enumerates the supported shape geometries. It does not explicitly differentiate itself from the sibling setLayerMask, so an agent must infer the add-vs-modify distinction, but the core purpose is unambiguous.

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?

No when-to-use guidance is given. The presence of a sibling setLayerMask makes the omission meaningful: nothing tells the agent when to create a mask versus update an existing one, nor what prerequisites (comp/layer targeting) must hold.

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