design_add_starfield

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

With no annotations, the description does useful work by disclosing what the tool renders: magnitude-based stars, optional Milky Way band, constellation hints, and variation in size, brightness, and color temperature. It does not describe layer side effects, ordering, interaction with existing starfields, or what a caller can expect after the layer is added.

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?

The description is three tight sentences and front-loads the core action before rendering traits and presets. The preset sentence is partially redundant with the enum in the schema, but it still helps an agent quickly grasp the available visual modes.

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 10-parameter additive design-layer tool with no output schema and full schema coverage, the description provides enough context to select and call it: it explains the visual output and enumerates presets. It falls short of fully explaining integration with the layer stack or existing sky layers, which keeps it from a perfect score.

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 100%, so the schema already documents all 10 parameters and defaults. The description's preset list mirrors the schema enum and its rendering notes loosely map to parameters like starCount and starColor, but it adds no syntax, default, or interaction details beyond 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?

The description gives a specific verb (Add), a precise resource (star field layer), and a scene context (night sky scenes), plus rendering traits that separate it from a generic sky tool. It never names the closest siblings, such as design_add_sky or design_add_celestial, so differentiation is implicit rather than explicit.

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 only implied by 'for night sky scenes.' There is no statement of when to choose this over design_add_sky, design_add_celestial, or other atmosphere tools, and no exclusions or prerequisites are mentioned.

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