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tbrito88
by tbrito88

Set Parameter

set_parameter
Idempotent

Update an existing Fusion 360 user parameter's numeric value by name, using the unit it already declares; adjust dimensions, angles, or coordinates directly.

Instructions

Update the value of an existing user parameter. Unless a parameter says otherwise, lengths and coordinates are in cm (not mm) and angles in degrees.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
nameYesParameter name
valueYesNew numeric value, expressed in the unit the parameter already declares

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A3.7/5.0
Behavior3/5

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

Annotations already declare non-read-only, idempotent, non-destructive behavior, so the safety profile is covered. The description adds the useful unit convention (cm and degrees by default), but says nothing about rebuild/regeneration side effects or permission requirements.

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?

Two sentences, no waste, with the core action front-loaded and the unit caveat properly placed second.

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 two-parameter mutation whose safety annotations are already supplied, the description plus schema is nearly complete. The only minor gap is whether setting a value triggers a model rebuild, which an agent might care about.

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 coverage is 100%, so the baseline is 3. The description goes beyond the schema by stating the default unit convention (cm for lengths, degrees for angles), clarifying the schema's more abstract 'unit the parameter already declares'.

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 ('Update the value') and resource ('existing user parameter'), which cleanly separates it from create_parameter, delete_parameter, and get_parameters. It is clear but does not explicitly name those siblings as alternatives.

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 word 'existing' implies the parameter must already exist, hinting at the boundary with create_parameter, but there is no explicit when-to-use guidance or stated prerequisites. Usage is only implied.

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