design_create_brush

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

No annotations are provided, so the description carries the full burden, and it does disclose the mutation target (the layer's brushes array) and the resulting capability (referenceable by id). It says nothing about collision behavior for an existing brush id, what happens if layerId is invalid, persistence across sessions, or what the call returns.

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 sentences, zero filler, and the mutation target is stated first before the follow-up usage note. Nothing here repeats the schema or the tool name verbatim.

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 2-parameter tool with a fully documented nested schema and no output schema, the description covers purpose and lifecycle adequately. But with no annotations and no output schema, an agent still cannot tell whether the call returns the created brush, errors on duplicate ids, or mutates an existing definition - gaps the description should fill.

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% and the nested BrushDefinition object is documented field-by-field in the schema, including the tipTexture base64 requirement, so the schema does the heavy lifting. The description adds only the framing that `brush` is a custom brush definition and that its `id` is the reference key; it adds nothing about layerId semantics beyond what the schema states.

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 ('Add') and resource ('custom brush definition') plus the exact destination ('a painting:stroke layer's brushes array'), which is more precise than a generic 'create brush'. It also names the downstream consumer (brush_stroke), which separates creation from use, though it never contrasts itself with design_list_brushes or design_set_blend-style siblings.

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 second sentence gives clear workflow context: create the brush here, then reference it by id in brush_stroke calls. That tells an agent when this tool belongs in a sequence. It stops short of any exclusion or precondition (e.g., whether the layer must already exist or be a stroke layer).

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