design_design_add_water_reflection

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 a genuine behavioral trait — Fresnel-based strength that is stronger at glancing angles — which is useful. However, it never states that this is a mutating 'add' operation creating a new layer, whether it's reversible, or what happens if no waterline/water surface exists.

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 tight sentences, front-loaded with the core action, followed by the Fresnel behavior and preset list. Minor waste: enumerating the four presets duplicates the schema enum exactly rather than explaining when to choose each.

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 6-parameter mutation tool with no annotations and no output schema, the description covers the concept but not the operational essentials: it doesn't say what is created (a layer?), what the result looks like, or how it interacts with existing water surfaces. Adequate but with clear gaps.

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 all six parameters are documented in the schema and the baseline is 3. The description repeats the four preset IDs verbatim from the enum without adding selection guidance, and says nothing about skyColor, terrainColor, waterlinePosition, reflectionStrength, or 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+resource: 'Add a water reflection layer that mirrors terrain and sky below the waterline.' That's clearly distinguishable in substance, but the description never mentions the near-duplicate siblings design_add_reflection and design_add_water_surface, leaving the agent to guess which reflection 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?

No when-to-use, when-not-to-use, or prerequisite guidance. It doesn't say that a water surface should exist first, nor how this differs from design_add_reflection or design_add_water_surface. The preset list hints at intended looks but is not usage guidance.

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