CAD MCP Server

by 652036

Overview Schema Source Related Servers Discussions Admin

create_arc

Creates a circular arc in a CAD drawing using center coordinates, radius, and start/end angles in radians, with optional unit and layer.

Instructions

Create a circular arc: centre (cx,cy), radius, startAngle and endAngle in radians (counterclockwise from +X; mathematical Y-up). Radius uses unit (default mm). Stored as coords [cx,cy,r,startAngle,endAngle] in mm.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "cx": "<cx>",
      "cy": "<cy>",
      "radius": "<radius>",
      "startAngle": "<startAngle>",
      "endAngle": "<endAngle>"
    },
    "name": "create_arc"
  }
}

Input Schema

Name	Required	Description	Default
`cx`	Yes
`cy`	Yes
`unit`	No
`layer`	No
`radius`	Yes
`endAngle`	Yes
`startAngle`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 13, 2026

TDQS

A4.2/5.0

Behavior4/5

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

With no annotations, the description carries the full burden. It discloses key behavioral traits: angles are in radians, counterclockwise from +X, Y-up coordinate system, radius uses the unit parameter (default mm), and the arc is stored as coords [cx,cy,r,startAngle,endAngle] in mm. It does not mention layer behavior or side effects, but the coordinate and storage conventions are substantial context beyond the schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the core action and immediately followed by essential coordinate and unit conventions. Every sentence earns its place with no redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a creation tool with 7 parameters, no annotations, and no output schema, the description provides enough to call it correctly: geometry, coordinate system, angle units, default unit, and storage format. It could mention layer behavior or return semantics, but those gaps are minor.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It meaningfully explains cx, cy, radius, startAngle, endAngle, and unit (default mm, angle semantics in radians). It omits any explanation of the 'layer' parameter, which is the only notable gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Create') and resource ('circular arc') and lists the defining parameters. It clearly distinguishes this tool from siblings like create_circle, create_ellipse, and create_spline by naming the exact geometry produced.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage ('Create a circular arc') but provides no explicit when-to-use or when-not-to-use guidance, nor does it name alternative tools such as create_circle or create_polyline for related geometry.

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

Deploy Server