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draw_arc

Create a circular arc counter-clockwise from a start angle to an end angle by specifying center, radius, and optional layer, color, or linetype.

Instructions

Draw a circular arc counter-clockwise from start_angle to end_angle.

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": {
      "center": "<center>",
      "radius": "<radius>",
      "start_angle": "<start_angle>",
      "end_angle": "<end_angle>"
    },
    "name": "draw_arc"
  }
}

Input Schema

Name	Required	Description
`color`	No	ACI 0-256 or name (red, yellow, green, cyan, blue, magenta, white, bylayer)
`layer`	No	Target layer (created if missing). Default: current layer.
`center`	Yes	[x, y] or [x, y, z]
`radius`	Yes
`linetype`	No	Linetype name, e.g. CONTINUOUS, DASHED, CENTER, HIDDEN
`end_angle`	Yes	Degrees, CCW from +X
`start_angle`	Yes	Degrees, CCW from +X

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 28, 2026

TDQS

B3.3/5.0

Behavior3/5

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

Annotations already declare this is a mutating (readOnlyHint=false), non-idempotent, non-destructive operation within a closed world, so the safety profile is covered. The description adds the CCW sweep direction, which is genuine behavioral context, but it says nothing beyond that about side effects, layer creation, or undo behavior.

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?

A single front-loaded sentence with no filler; the direction and endpoints are stated immediately and nothing is wasted.

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

Completeness3/5

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

An output schema exists so return values need not be explained, and the schema covers most parameters. However, for a 7-parameter geometry mutation tool the description is thin on the drawing-state context (which drawing, default layer) and the angular convention's interaction with the two required angles.

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

Parameters3/5

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

Schema coverage is 86%, so the schema already documents center, color, layer, linetype, and the angle conventions. The description only restates the start/end angle relationship, adding no syntax or units beyond what the schema fields provide; baseline 3 is appropriate.

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

Purpose4/5

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

States a specific verb (draw) and resource (circular arc) with the orientation semantics (counter-clockwise from start_angle to end_angle). It is clearly distinguishable from draw_circle, draw_ellipse, and draw_line by name and shape, though it does not explicitly contrast itself with those siblings.

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

Usage Guidelines2/5

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

No guidance on when to choose an arc over draw_circle, draw_ellipse, or a polyline approximation, and no prerequisites or constraints (e.g. which drawing must be open, current layer behavior) are given. Usage must be inferred entirely from the name.

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