design_add_particles

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

With no annotations, the description carries the full disclosure burden. It does add real behavioral context (auto-resolution of layer type from preset, preset inventory size), but omits whether the layer is appended to the current layer stack, whether it requires an open sketch, whether defaults are overridden destructively, and what identifier is returned for later design_set_particle_* calls.

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?

Three short sentences, zero filler, and the core action is front-loaded in the first clause. The auto-resolution detail and preset count each earn their place as non-obvious facts.

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 an 8-parameter mutation tool with 100% schema coverage and no annotations, the description covers the essential unknown (how a preset maps to a layer type). The remaining gap is scene context: nothing says where the new layer lands in the existing stack or what handle comes back for subsequent particle tuning.

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%, with all 8 parameters and 3 enums documented in-schema, so the baseline is 3. The description adds the semantic link between the required 'preset' enum and the resulting layer type, plus the scale of the preset library, but says nothing about the override parameters (color, count, opacity, seed) beyond what the schema already 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 ('particle layer') and explains the non-obvious routing mechanism: the preset category determines layer type (falling, floating, scatter, mist, trailing, flow, mark-field). This distinguishes it from generic layer siblings like design_add_layer. It does not explicitly contrast with overlapping siblings such as design_add_flow_lines or design_add_mark_field, which the 'flow'/'mark-field' categories shadow.

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?

Usage is implied: supply one of the 46 presets by name and the type is chosen automatically, and the '46 presets available' note hints at a discovery flow via design_list_particle_presets. But no explicit when-to-use, prerequisites (e.g., an open sketch), or when to prefer a sibling like design_add_flow_lines or the post-hoc design_set_particle_style tools.

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