Create a Model variable (MVar) to set simulator or precision parameters for IC-CAP measurements.
Create a Model variable (MVar). Common uses: SIMULATOR, PARAMETER_PRECISION, WORKING_PRECISION.
| Name | Required | Description | Default |
|---|---|---|---|
| value | No | Initial value | |
| var_path | Yes | Full path, e.g. '/model_name/SIMULATOR' |
Changes observed during successful MCP inspections.
v0.2.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure, but it only says 'create' and lists common uses. It does not mention whether the tool errors on duplicate paths, whether the parent model must already exist, whether the optional value defaults, or what side effects occur beyond creation.
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 compact, front-loads the core purpose, and includes only useful examples of common MVar names. Every sentence contributes value without repetition or filler.
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?
As a simple creation tool with complete parameter schema, the description is minimally adequate for invoking the tool. However, with no annotations and no output schema, it does not explain return values, error behavior, or preconditions, leaving some contextual 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%, and both parameters have clear descriptions in the schema itself. The tool description adds no additional parameter-level meaning, so the baseline score of 3 is appropriate.
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 verb and resource: 'Create a Model variable (MVar).' This clearly distinguishes it from sibling creation tools like dvar_create, svar_create, and ivar_create. The common-use examples further disambiguate the intended purpose.
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 implies usage by listing common MVar purposes such as SIMULATOR, PARAMETER_PRECISION, and WORKING_PRECISION. However, it does not explicitly state when to prefer this tool over alternatives or when not to use it, leaving the routing partially to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.