design_brush_stroke

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

With no annotations, the description carries the full burden; it does disclose that strokes append to an existing layer or trigger creation of a new one, and that inline custom brushes override brushId. It omits key mutation facts: whether existing layer content is preserved or replaced, what is returned (layer ID? stroke ID?), permission/type requirements for layerId, and undo implications.

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, front-loaded with the action and immediately followed by the layerId decision rule and brush-source options. No filler sentences.

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 9-parameter nested-schema mutation tool with no annotations and no output schema, the description covers targeting and brush sourcing but leaves the agent guessing about return values and constraints on the target layer. Adequate but with clear gaps for a drawing mutation.

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 each of the 9 parameters is documented in the schema, so the baseline is 3. The description adds only the detail that brushId spans 11 built-in presets or custom IDs, and repeats layerId's omit-to-create semantic already present in the schema.

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 and resource ("Create brush strokes on a painting:stroke layer") and explains the layer-targeting behavior. It doesn't distinguish itself from nearby siblings such as design_add_bristle_stroke, design_paint_layer, or design_create_brush, so an agent must infer which brush-stroke tool to pick.

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 layerId branch clearly defines two operating modes (append vs create new layer), which is implied usage guidance. But no alternatives are named — an agent gets no help choosing between this, design_add_bristle_stroke, design_paint_layer, or design_create_brush, nor any prerequisite about layer types.

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