list_variables

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

Annotations already mark it readOnly and closed-world; the description adds useful behavior beyond those: enumerates output kinds, flags state as settable, and documents port naming/units and control variable conventions. It does not mention pagination or result size, but 'Every variable path' signals exhaustiveness.

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 and front-loaded: the first sentence states exactly what is returned, and the second condenses a taxonomy of variable kinds into a few lines. No filler or repetition of the schema.

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 read-only annotation, an output schema, and only two parameters, the description carries enough domain context to call the tool correctly. The main residual gap is clarifying what system_id refers to, but sibling naming and the required field make that reasonably inferable.

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?

system_id is undocumented in the schema and not explained in the description, leaving a gap at 50% coverage. However, the description does add semantic value for the component parameter by defining the special 'control' value and the port path patterns that filter results.

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 identifies the resource and output: 'Every variable path with kind, unit, limits and description.' It is clearly about variables rather than components or systems, which separates it from list_components and get_system, though it lacks an explicit imperative verb.

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 given about when to choose this tool over list_components, describe_component, or other siblings. The only conditional guidance ('component='control' lists them') is an internal parameter detail, not usage context.

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