Set control point positions on a spline curve, including handles for Bezier or weights for NURBS/Poly.
Set control point positions on a spline. Each entry: {co: [x,y,z], handle_left: [x,y,z], handle_right: [x,y,z]} for Bezier, or {co: [x,y,z,w]} for NURBS/Poly.
| Name | Required | Description | Default |
|---|---|---|---|
| object | Yes | ||
| points | Yes | ||
| spline_index | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0+hardened.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must disclose behavior. It only states 'Set control point positions' without mentioning whether it replaces existing points, whether the spline index is zero-based, whether handles are optional for Bezier, or what coordinate system is used. This leaves critical behavior to guesswork.
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 two sentences with no filler: the purpose is first, followed by a compact data format specification. Every phrase 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?
With three required parameters and no annotations, the description leaves out the meaning of 'object' and 'spline_index', and does not state whether this operation replaces or edits existing control points. It also lacks information about the output, though an output schema exists. The tool is incomplete for an agent to use confidently.
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 description explicitly documents the structure of the 'points' parameter for Bezier and NURBS/Poly entries, which adds meaning beyond the empty schema. However, it does not explain the 'object' or 'spline_index' parameters, so the compensation is only partial for the 0% schema coverage.
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 action ('Set control point positions') on a specific resource ('a spline'), and the entry format distinguishes it from generic curve property setters. Though it doesn't name an alternative sibling, the subject matter is unique enough to identify the tool's purpose.
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?
Gives no guidance on when to use this tool vs alternatives like set_curve_property. The description only says what it does, not which situations call for it, nor any prerequisites or exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.