create_parameterCreate a new user parameter in Fusion 360 by defining its name, value, and unit, plus an optional comment.
Create a new user parameter
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Parameter name | |
| unit | Yes | Unit expression (e.g. 'mm', 'cm', 'in', 'deg') | |
| value | Yes | Numeric value | |
| comment | No | Optional comment |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate this is a non-read-only, non-idempotent, non-destructive operation (readOnlyHint=false, idempotentHint=false, destructiveHint=false). The description adds minimal behavioral context beyond this—it doesn't specify what happens on duplicate names, whether creation is immediate, or any permission requirements. It doesn't contradict annotations, but provides little extra value given their coverage.
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. It's front-loaded with the core action and resource, making it easy to parse quickly. Every word earns its place without redundancy.
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 lack of an output schema and the tool's mutation nature (creating a parameter), the description is somewhat incomplete. It doesn't hint at what the tool returns (e.g., success confirmation, the created parameter object, or an error). However, annotations cover safety aspects, and the schema is well-documented, making it minimally adequate but with room for improvement in output expectations.
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 documentation for all four parameters (name, value, unit, comment). The description adds no additional parameter semantics beyond what's in the schema, such as format constraints or examples beyond the unit field's schema description. This meets the baseline for high schema 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 ('Create') and resource ('new user parameter'), making the purpose immediately understandable. However, it doesn't differentiate this from sibling tools like 'set_parameter' or 'get_parameters', which would require explicit comparison to achieve a perfect score.
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?
The description provides no guidance on when to use this tool versus alternatives like 'set_parameter' (which might update existing parameters) or 'get_parameters' (which retrieves them). There's no mention of prerequisites, context, or exclusion criteria, leaving the agent with insufficient usage direction.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.