add_user_defined_variables

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

With no annotations, the description carries the behavioral burden. It discloses that the element is created, values are set once before execution, and parent determines scope. It does not mention override behavior, uniqueness constraints, or side effects on existing variables, leaving some room for uncertainty.

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?

Two tight sentences deliver the resource, placement options, and timing behavior with no filler. The most decision-relevant information (parent context) is front-loaded.

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?

For a simple creation tool with no output schema, the description covers what the tool creates, where it places it, and when values are evaluated. It omits preconditions like plan existence or invalid parent handling, but these are not critical for an agent to make a correct first call.

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%, so the description must compensate. It adds meaning for parentId by explaining TestPlan root vs Thread Group scoping, but it does not explain planId, the variables array structure, or how the optional name behaves. This is partial compensation only.

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 uses a specific verb ('Add') and names the exact resource ('User Defined Variables config element') plus the valid parent contexts. It clearly distinguishes this from add_user_parameters by emphasizing that values are set once before the test starts.

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 provides clear placement guidance: TestPlan root for global variables versus Thread Group for scoped ones. It implies the right time to use this tool (static, pre-test values) but does not explicitly name alternatives or state when not to use it.

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