create_sketchCreates a sketch on the XY, YZ, or XZ plane with an optional offset, so you can start 2D geometry on a chosen plane.
Create a new sketch on xy/yz/xz plane, optionally offset. Unless a parameter says otherwise, lengths and coordinates are in cm (not mm) and angles in degrees.
| Name | Required | Description | Default |
|---|---|---|---|
| plane | No | xy | |
| z_offset | No | Offset distance from the plane (cm) |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare this is a non-readonly, non-idempotent, non-destructive mutation, so the safety profile is covered. The description adds genuinely useful context—units are cm not mm and angles are degrees—but says nothing about what is returned (sketch identity) or what happens on duplicate/failed creation.
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?
Two compact sentences with the core action front-loaded and the units caveat second. Nothing is wasted, though the appended units clause could be tightened.
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 mutation tool with no output schema and only partial param coverage, the unit convention helps but leaves gaps: no return value, no prerequisite design context, no interaction with the sketch's parent body/component.
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 coverage is 50%: z_offset is documented in the schema while plane relies on its enum. The description reinforces the cm unit for lengths/offsets, which is added value, but it does not explain the plane enum or the offset's direction/sign convention.
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 (create sketch) and constrains it to the three named planes with an optional offset, so an agent can tell it apart from primitives like create_box or curve tools like draw_line. It does not differentiate itself from the related create_construction_plane sibling, but the resource is unambiguous.
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 when-to-use or when-not-to-use guidance is given; it never says whether this should precede draw_rectangle/draw_line or how it relates to create_construction_plane. The unit convention is the only contextual rule offered.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.