Create a DUT variable to override simulator settings at the device level. Specify the full variable path and optional initial value to define custom DUT parameters.
Create a DUT variable (DVar). Common uses: DUT-level overrides of SIMULATOR, etc.
| Name | Required | Description | Default |
|---|---|---|---|
| value | No | Initial value | |
| var_path | Yes | Full path, e.g. '/model/dut/VAR_NAME' |
Changes observed during successful MCP inspections.
v0.2.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description bears the full burden of behavioral disclosure. It does not say what happens if var_path already exists, whether creation is destructive or reversible, whether permissions are needed, or what response the caller can expect—only that it creates a DVar with common override use.
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?
Two short sentences put the core action and an example use case up front with no redundant filler. The trailing "etc." adds slight vagueness but does not undermine readability.
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?
For a simple two-parameter create tool with complete schema descriptions, the basic call contract is visible. However, with no annotations and no output schema, the description leaves important operational behavior (duplicate path handling, return value, side effects) unspecified, so it is only minimally complete.
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%, so parameter meaning is already fully documented. The description adds the DUT-level override context but no additional syntax, constraints, or relationships between value and var_path beyond the schema.
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 names a specific action (Create) and resource (DUT variable/DVar) and adds a practical use case (DUT-level overrides of SIMULATOR). It is distinguishable from related siblings like dvar_set by the verb, though it does not explicitly call out the distinction.
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?
"Common uses" indicates when the tool applies, but it offers no explicit guidance on when to choose dvar_create over alternatives such as dvar_set, dut_create, or other resource-specific create tools. Usage context is implied rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.