rhino_add_control_point

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

With no annotations, the description carries the behavioral burden. It states the core side effect (adds a control point to the end) and the prerequisite (a selected NURBS curve), but does not disclose whether the curve is modified in place, how the selection is resolved, or any failure conditions. The primary mutation is clear, though.

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?

A single, front-loaded sentence with no filler. Every word contributes either the target, the position, or the prerequisite, making it easy for an agent to parse quickly.

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 zero-parameter tool with an output schema, this is nearly complete: it identifies the object type, selection state, and insertion location. It would be stronger with an explicit note about modifying the original object or requiring an active selection, but the simplicity of the tool and presence of the output schema cover most 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?

The input schema has zero properties, so there are no parameter descriptions to supplement. The description adds the essential implicit parameter: the operation applies to a selected NURBS curve at its U-direction endpoint, which is exactly the guidance an agent needs when no explicit arguments are accepted.

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?

Description uses a precise verb ('Add') and names the specific resource ('control point'), the target ('selected NURBS curve'), the position ('to the end'), and the direction ('U direction'). This clearly distinguishes it from siblings like rhino_remove_control_point and rhino_set_control_points.

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 only usage cue is the operation itself — an agent can infer it should be used when a control point needs to be appended to a NURBS curve. It does not explicitly state when to prefer it over rhino_set_control_points or rhino_edit_points_on, nor does it mention exclusions or prerequisites beyond selection.

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