control-expert-mcp

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list_variables

List global variables from a Control Expert project, showing type, comment, address, and initial value. Filter by variable name with case-insensitive substring matching.

Instructions

List global variables with type, comment, topological address (%MW..., %I..., etc.) and initial value. name_filter does a case-insensitive substring match on the variable name.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "list_variables"
  }
}

Input Schema

Name	Required	Description	Default
`name_filter`	No
`max_results`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jun 14, 2026

TDQS

A3.8/5.0

Behavior3/5

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

No annotations are provided, so the description carries the full burden. It makes the read-only nature clear with 'List' and discloses the case-insensitive substring filter behavior. It does not mention prerequisites such as requiring an open project, result ordering, or pagination handling.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the core behavior and followed by the filter detail. There is no filler or redundant restating of the tool name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple read-only list tool with two optional parameters, the description covers the relevant output fields and the filtering behavior well. Minor gaps are the lack of explanation for max_results semantics and the absence of an explicit output format, but these are not critical given the simplicity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It explains name_filter's case-insensitive substring matching, which adds real meaning beyond the schema. However, it leaves max_results undocumented beyond its default in the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('List') and resource ('global variables') and enumerates the returned attributes: type, comment, topological address, and initial value. It clearly distinguishes this read-oriented listing tool from sibling tools like create_variable, update_variable, and delete_variable.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies when to use the tool: when one needs to enumerate global variables, optionally filtered by name. However, it does not explicitly mention alternatives or provide when-not-to-use guidance, such as when to use list_data_types instead.

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

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