Read a RAPID variable's live runtime value through RWS by providing task, module, and variable names, enabling real-time inspection of controller data.
Read a RAPID variable's live runtime value via RWS
| Name | Required | Description | Default |
|---|---|---|---|
| task | Yes | ||
| module | Yes | ||
| variable | Yes |
Changes observed during successful MCP inspections.
v3.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the full burden. It does not disclose what happens if the variable does not exist, if there are read permissions required, or any error conditions. The read-only nature is implied but not explicit.
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, front-loaded sentence that gets to the point quickly. However, it is too concise and lacks necessary detail, but for a simple tool, it is acceptably concise.
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 no output schema, no annotations, and three required parameters with no documentation, the description is incomplete. It does not explain return format, error handling, or how to use the parameters effectively. The tool is used in a complex RWS environment, and the description lacks essential context.
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 0%, and the description adds no meaning to the parameters 'task', 'module', or 'variable'. It does not explain what values they accept, format constraints, or how to specify them. The description fails to compensate for the lack of schema descriptions.
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 verb 'Read', the resource 'RAPID variable', and the context 'live runtime value via RWS'. It distinguishes from sibling tools like rws_write_variable, rws_read_module, and rs_read_variable by specifying RWS and the exact action.
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 does not provide any guidance on when to use this tool versus alternatives. It lacks prerequisites, when-not-to-use scenarios, or comparisons with siblings like rs_read_variable, which might be used in simulation context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.