Expand a debugger variable to reveal its child components: structure fields, table rows, or referenced objects. Takes the variable ID from the debugger variables list.
Open one variable that has parts: the fields of a structure, the rows of an internal table, what a reference points at. Takes the variable id from debuggerVariables.
| Name | Required | Description | Default |
|---|---|---|---|
| parent | No | The parent variable name. |
Changes observed during successful MCP inspections.
v0.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds that it opens composite variables, but does not explain behavior like what happens if the variable has no parts, or whether it returns the parts or just expands them. Since annotations handle the main behavioral trait, the description provides modest additional context.
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 two sentences, concise and front-loaded with the main purpose. It wastes no words and is easy to scan. It could be slightly more structured (e.g., bullet points) but is effective.
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?
The tool is relatively simple, but the description lacks details on the return value or output format (no output schema). The parameter ambiguity (array vs single id) and lack of explanation about what 'parts' means or how the tool behaves for different variable types leave an agent with insufficient information to call it reliably. Given the debugger context, more context is expected.
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?
The schema describes the parameter 'parent' as an array of 'The parent variable name', while the description says 'Takes the variable id from debuggerVariables' – a mismatch in terminology (name vs id) and no clarity on how the array is used. With 100% schema coverage, the baseline is 3, but the description introduces confusion about the parameter's meaning, so it actually detracts from clarity. The array type is also unexplained, suggesting possible multiple parents but not elaborated.
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 tool opens a variable that has components (structure fields, internal table rows, reference targets). This is a specific verb and resource. However, it does not explicitly distinguish itself from the sibling debuggerVariables, which might also list variables, so it does not fully differentiate from likely alternatives.
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 the tool should be used after obtaining a variable id from debuggerVariables, giving a prerequisite context. However, it does not explicitly say when to use this tool versus other debugger tools (e.g., debuggerStep) or when not to use it. The guidance is implicit rather than explicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.