set_parameterUpdate the numeric value of an existing user parameter in Fusion 360 to adjust model dimensions or automation settings.
Update the value of an existing user parameter
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Parameter name | |
| value | Yes | New numeric value |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations indicate this is a non-destructive, idempotent mutation tool. The description adds value by specifying it updates 'existing' parameters, implying a prerequisite, but does not elaborate on behavioral traits like error handling or side effects beyond what annotations cover.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, efficient sentence with no wasted words, front-loading the core action. It is appropriately sized for the tool's straightforward purpose.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's moderate complexity (mutation with two parameters), annotations provide safety context, but the description lacks details on output or error cases. Without an output schema, it should ideally mention return values or success indicators, leaving some gaps.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, with clear parameter documentation. The description adds minimal semantics by implying 'name' identifies an existing parameter and 'value' is numeric, but this is largely redundant with the schema, meeting the baseline for high coverage.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action ('Update') and target ('existing user parameter'), making the purpose evident. However, it does not differentiate from sibling tools like 'create_parameter' or 'delete_parameter', which would require specifying it modifies rather than creates or removes.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided on when to use this tool versus alternatives such as 'create_parameter' or 'delete_parameter'. The description lacks context about prerequisites (e.g., parameter must exist) or exclusions, offering minimal usage direction.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.