Fusion360 Live MCP

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Create Parameter

create_parameter

Creates a new user parameter in Fusion 360 to define dimensions or angles with a name, numeric value, unit, and optional comment.

Instructions

Create a new user parameter. 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": {
      "name": "<name>",
      "value": "<value>",
      "unit": "<unit>"
    },
    "name": "create_parameter"
  }
}

Input Schema

Name	Required	Description
`name`	Yes	Parameter name
`unit`	Yes	Unit the value is given in (e.g. 'mm', 'cm', 'in', 'deg'). Empty means unitless.
`value`	Yes	Numeric value, expressed in `unit`
`comment`	No	Optional comment

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 30, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the safety profile is already covered. The description adds useful behavioral context by stating the default unit convention: lengths/coordinates are in cm not mm, and angles in degrees. It still does not disclose duplicate-name behavior or return values.

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 then the important unit convention. It is concise and has no filler.

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 four-parameter creation tool with full schema coverage and annotations, the description supplies the essential purpose and unit context. It omits return-value information, but that is a minor gap given the simplicity of the operation.

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 100%, so the schema already documents each parameter. The description adds meaning beyond the schema by clarifying the default unit convention for values, which is relevant when using the required 'unit' parameter.

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 and resource: 'Create a new user parameter.' The word 'new' also distinguishes it from set_parameter, which likely modifies an existing parameter.

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?

Usage is implied by 'Create a new user parameter' — use it when a parameter does not already exist. However, the description does not explicitly say when not to use it or name set_parameter as the alternative for existing parameters.

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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