rhino_surface_normal_at

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

Annotations already set readOnlyHint: true, so no further safety disclosure is needed. The description adds behavioral context about normalization and internal computation of actual parameters, which is valuable beyond the 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?

The description is extremely concise: two sentences that convey all necessary information without any fluff. Every word earns its place.

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?

Given the tool's simplicity (evaluate normal at a point), the description covers the essential normalization and parameter handling. An output schema is present, so return values need not be explained. The description is complete.

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?

The input schema includes descriptions for u and v ('Normalised U parameter (0 .. 1).'). The description adds extra meaning by clarifying that the actual parameters are computed internally so the LLM doesn't need to know domain bounds, which aids correct usage.

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 clearly states that the tool evaluates the surface unit normal at a normalized (u,v) coordinate. It uses a specific verb ('evaluate') and resource ('surface unit normal'). Among siblings, it is distinct from tools like rhino_surface_curvature_at (curvature) and rhino_evaluate_surface (point evaluation).

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 that u and v are 0..1 ratios and that domain bounds are handled internally, guiding the agent on how to provide normalized parameters. It does not explicitly state when to use this tool versus alternatives, but the context is clear.

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