design_add_sky

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

There are no annotations, so the description carries the full behavioral burden. It implies a layer-creating mutation and notes the default preset ('noon' is only in the schema, not in the description text) and a desired stack position, but it does not disclose permissions, reversibility, whether the tool auto-reorders layers, or what is returned. This is useful context for a simple add operation, but not complete for a mutation with no annotations.

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 waste, front-loaded with the purpose. The preset-vs-custom choice and stack-order constraint follow in logical order.

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 tool with five optional, fully documented parameters and no output schema, the description covers the core action, the preset approach, the custom-color alternative, and stack placement. It is nearly complete, though it omits sibling routing and the interaction with existing layers or an existing sky layer.

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 the baseline is 3. The description mentions presets and custom zenith/horizon/haze colors, which maps to some parameters, but adds no syntax or format detail beyond the schema and does not mention the `name` parameter.

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: 'Add a sky gradient layer to the sketch.' That is clear enough to distinguish it from generic layer tools, but it does not differentiate from nearby siblings like design_add_gradient, design_add_haze, design_add_atmosphere, or design_add_fog_layer, so an agent must infer the boundary itself.

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 description explains parameter choices ('Choose a time-of-day preset ... or set custom zenith/horizon/haze colors') and gives a stack-placement rule ('Sky layers should be at the bottom of the layer stack'). However, it never says when to use this tool instead of siblings such as design_add_atmosphere, design_add_haze, or design_add_gradient.

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