Fusion360 Live MCP

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Create Sphere

create_sphere

Creates a non-parametric sphere primitive in Fusion 360 from a required radius and optional center, with centimeter and degree defaults.

Instructions

Create a sphere primitive (non-parametric via TemporaryBRepManager) 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": {
      "radius": "<radius>"
    },
    "name": "create_sphere"
  }
}

Input Schema

Name	Required	Description	Default
`radius`	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

B3.4/5.0

Behavior3/5

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 safety profile is covered. The description adds the non-parametric BRep nature and the unit convention, which is genuine extra context, but says nothing about where the body is created (active component/design) or whether it is unlinked geometry.

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?

Two tight sentences with the core action front-loaded and the unit caveat second. No filler, though the parenthetical implementation detail could arguably be trimmed.

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?

For a simple 4-parameter primitive with no output schema, the description covers units and the geometry type, which is the essential information. It leaves open the resulting body's context (component, naming, editability), a minor but real gap for a creation tool.

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 description coverage is 0%, so the schema documents only types and defaults. The description compensates for units (cm and degrees) for radius and center coordinates, which is valuable, but it explains none of the individual parameters' meaning or geometry.

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 and resource ('Create a sphere primitive') and adds a meaningful qualifier that it is non-parametric via TemporaryBRepManager, distinguishing it from a parametric solid. It does not explicitly contrast with the other primitive creators (create_box, create_cylinder, create_torus), but the name and mechanism make the target unambiguous.

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 mention of 'non-parametric' implies when this is appropriate versus a parametric primitive, but the description never states when to choose it or what alternatives exist. Usage is only inferable, not stated.

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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