rhino_variable_fillet

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

With no annotations, the description carries the behavioral burden and does disclose the key non-obvious traits: the radii are supplied as option overrides, edge selection is interactive, and a command-result dict is returned. It does not detail prerequisites or side effects on existing geometry, but the core interaction warning is present.

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 definition is compact and front-loaded: purpose, interaction behavior, args, and return type each get one short section with no filler. Minor redundancy and the ghost controller parameter keep it from a perfect structure score.

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 two-parameter interactive tool it covers the essentials: what is created, which radii to pass, that edge selection is interactive, and the return shape. Still, it omits whether the user must preselect the two surfaces/edge, and it does not route to the constant-radius sibling, so an agent is left to infer some setup steps.

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 schema has no parameter descriptions, and the description gives meaning to start_radius and end_radius as radii at the start/end of the edge, which is genuinely helpful. The Args block also lists a controller parameter that does not exist in the input schema, creating a confusing mismatch that prevents a higher score.

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 opens with a specific verb and resource: 'Create a variable-radius fillet surface between two surfaces.' The 'variable-radius' qualifier and the start/end radii distinction separate it from the constant-radius fillet_surface siblings without needing to name them.

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?

It tells the agent that radii are option overrides and that edge selection will be interactive, so the agent knows user participation is required. However, it never explicitly states when to prefer this over rhino_fillet_surface or rhino_variable_blend_srf, so the when-to-use guidance remains mostly implied.

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