Fusion360 Live MCP

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Create Box

create_box

Creates a non-parametric box primitive in Fusion 360 from length, width, and height, positioned by center X/Y and bottom-face Z. Use it to add quick solid geometry to a CAD model.

Instructions

Create a box primitive (non-parametric via TemporaryBRepManager). center_x/center_y are the box CENTER, but center_z is its BOTTOM face: the box spans center_z .. center_z + height (confirmed live: center_z=6, height=12 gave Z 6..18). Unless a parameter says otherwise, lengths and coordinates are in cm (not mm) and angles in degrees.

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": {
      "length": "<length>",
      "width": "<width>",
      "height": "<height>"
    },
    "name": "create_box"
  }
}

Input Schema

Name	Required	Description	Default
`width`	Yes
`height`	Yes
`length`	Yes
`center_x`	No
`center_y`	No
`center_z`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 30, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the mutation/safety profile is largely covered. The description adds non-obvious behavioral context that annotations cannot: the center_z-as-bottom-face convention with a live-verified example, plus the cm/degree unit system. It stops short of describing side effects such as whether repeated calls stack bodies or which component receives the result.

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

Conciseness4/5

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

Three dense sentences, front-loaded with the core purpose and non-parametric caveat before the parameter/unit details. Every sentence earns its place, though the parenthetical source attribution adds slight noise.

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 6-parameter mutation tool with no output schema and 0% schema description coverage, this covers the highest-risk ambiguities (units, center convention). It does not address what the call returns or the default placement context, which would matter for an agent chaining calls.

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 carry the load, and it does: it disambiguates the three center_* parameters (XY center vs Z bottom face) with a concrete numeric example and specifies the unit system (cm, degrees) that the schema leaves entirely unstated. length/width/height semantics are left to be inferred from names.

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?

States a specific verb and resource ('Create a box primitive') and immediately qualifies the implementation mode ('non-parametric via TemporaryBRepManager'), which is exactly what distinguishes it from the sibling create_box_parametric. An agent can select correctly without opening either schema.

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 parenthetical '(non-parametric via TemporaryBRepManager)' implies when this tool is appropriate versus its parametric sibling, but it never names create_box_parametric or states the condition explicitly ('use X if you need editable parameters'). Usage is therefore implied rather than directed.

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

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