Create GTM Variable

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

Annotations are minimal (all flags false) and provide no safety or side-effect hints. The description only states the create action and enumerates valid type codes. It does not disclose what happens after creation (e.g., response format, persistence), permission requirements, or any side effects. For a mutation tool, this is insufficient transparency beyond the annotations.

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 extremely concise: one sentence stating the purpose followed by a bulleted list of variable types. It is front-loaded with the main action, and every line adds useful information. There is no redundancy or filler.

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 tool has 6 parameters and no output schema, the description is incomplete. It does not explain how to structure the 'parameters' array for different variable types, nor does it mention any required configuration for specific types. There is no guidance on expected outcomes or prerequisites. The type list is helpful but leaves major gaps for an agent to successfully invoke the tool.

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 covers all 6 parameters with descriptions (100% coverage). The description adds significant value by mapping shorthand type codes (c, v, jsm, etc.) to human-readable variable types (Constant, Data Layer Variable, etc.), which is not present in the schema beyond a bare enum list. This helps an agent construct correct type values.

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 action 'Create a new variable' with the resource 'in a workspace'. The verb and resource are specific, and it distinguishes from sibling create tools (e.g., create_tag, create_trigger) by naming the exact object type. The listing of common variable types further clarifies the tool's scope.

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 no explicit when-to-use or when-not-to-use guidance relative to sibling tools. It does not mention alternatives, prerequisites, or exclusions. The purpose is implied by the name, but there is no contextual direction for an agent deciding between this and other create tools or update/delete operations.

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