design_design_add_water_caustics

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

With no annotations, the description carries the full burden, and it does disclose a real behavioral trait: caustics are only visible when clarity exceeds 0.3. It says nothing about whether this mutates an existing water surface, whether it can be layered repeatedly, or what happens if no water exists — meaningful gaps for a mutation tool with zero annotation coverage.

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, front-loaded sentences, each carrying a distinct fact (what it does, when it shows, what options exist). No filler.

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?

There are no annotations and no output schema, and half the parameters are undocumented. The description covers the effect and one visibility rule but omits prerequisites (does a water surface need to exist?), seed behavior, and what waterlinePosition controls — not fully sufficient to invoke confidently.

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 coverage is 25%, so the description should compensate more. The clarity threshold adds genuine meaning to the clarity parameter, but the three preset names merely restate the enum with no explanation of their visual differences, and seed and waterlinePosition are left completely undocumented in both places.

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 effect ('Add underwater caustic light patterns'), which is more distinctive than most siblings. It does not explicitly distinguish itself from adjacent water tools like design_design_add_water_reflection or design_design_add_water_foam, leaving the agent to infer the boundary.

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 clarity > 0.3 condition is an implied usage constraint that helps decide whether caustics will render at all. There is no explicit guidance on when to pick this over water_reflection/foam/ice, nor on ordering relative to design_design_add_water_surface.

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