gtm_enable_built_in_variables

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

With no annotations provided, the description carries the full behavioral burden. It adds genuinely useful context beyond a simple mutation: enabling is type-based rather than creation-based, certain common variable types are enumerated, and the failure mode of triggers when variables are disabled is disclosed. It stops short of covering permissions or idempotence, but the provided context is meaningful.

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 concise and front-loaded. Every sentence earns its place: the action, the key concept ('enabled by type, not created'), the useful enumerated values, and the practical warning about trigger failure. No filler or redundant restatement of the tool name.

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 description explains what the tool does and why it matters, and an output schema exists, so return values need not be described. However, the semantics of the confirm flag and how account/container/workspace IDs are resolved or defaulted are left unexplained. An agent could still invoke the tool, but some operational context is missing.

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 helps for the required variable_types parameter by listing common accepted values, but it does not explain the meaning or role of confirm, account_id, container_id, or workspace_id. The core parameter is supported, but the optional parameters remain ambiguous.

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 opening sentence states a clear verb and resource: 'Turn on GTM built-in variables.' The phrase 'enabled by type, not created' explicitly differentiates this from creation-oriented siblings like gtm_create_entity or gtm_create_datalayer_variable, making the tool's scope unmistakable.

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 gives clear contextual guidance: click and form triggers 'silently fail' without the matching built-in variables, so enabling them is 'usually step one.' This tells an agent when to reach for this tool, though it does not name specific alternative tools or state explicit exclusion conditions.

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