shape_add_sphereAdd a sphere to Shape Studio geometry, using its bottom tangent point as origin in meters. Specify radius and optional position, name, color, surface ID, and segments.
Shape Studio: add a sphere (origin = bottom tangent point, m).
| Name | Required | Description | Default |
|---|---|---|---|
| r | Yes | ||
| at | No | ||
| name | No | ||
| color | No | ||
| surf_id | No | ||
| segments | No |
Changes observed during successful MCP inspections.
v4.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare this is a non-read-only, non-idempotent, non-destructive, non-open-world write. The description usefully adds the geometric convention ('origin = bottom tangent point, m'), which is real behavior beyond the annotations. It says nothing about undo/redo interaction or what happens to the document state, so it remains modest.
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 short line that is front-loaded with the action and module, with no filler. It is efficient, though the terseness borders on under-specification for a 6-parameter tool.
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 6-parameter creation tool with no output schema and minimal annotations, the description is too sparse. It omits the meaning/format of color, surf_id, segments, name, and the required radius, and gives no success/return expectations.
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 description coverage is 0% across 6 parameters, so the description must compensate. It only partially clarifies 'at' (as the bottom tangent origin) and implies units in meters; r, name, color, surf_id, and segments are entirely undocumented. Coverage of parameter meaning is far too thin for the parameter set.
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 verb+resource ('add a sphere') in a named module, clearly distinct from sibling shape_add_box/cylinder/cone/torus. It also adds the origin convention, which further pins down what is being created. However it does not contrast with related siblings like shape_add_torus or shape_add_arch beyond the resource name.
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?
No guidance on when to use this versus alternatives such as shape_add_cone, shape_add_cylinder, or boolean/revolve operations. The agent is left to infer selection purely from the resource name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.