List Enabled Built-In Variables

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so the safety profile is covered. The description adds that the tool lists enabled built-in variables and their role in tags/triggers, but does not disclose pagination behavior despite the page_token parameter, missing an opportunity to add value beyond 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 two sentences, front-loaded with the core purpose, and includes a useful contextual note. Every word earns its place with no redundancy or fluff.

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 read-only list operation with comprehensive annotations and full schema coverage, the description is mostly adequate. However, it fails to mention pagination even though a page_token parameter exists, and it does not explicitly distinguish against gtm_list_variables, leaving some ambiguity for a complex tool ecosystem.

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 coverage is 100%, with all parameters described (IDs and page_token). The description adds no parameter-specific detail beyond what the schema provides, so it meets the baseline but does not enhance understanding of parameters.

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 ('List the built-in variables currently enabled in a workspace') with specific resource and scope. It includes examples (Page URL, Click Classes) and differentiates from sibling tools by focusing on 'built-in' and 'enabled' status, contrasting with gtm_list_variables which would list custom variables.

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 context by explaining that tags and triggers can only reference enabled built-in variables, which helps an agent understand when to use this tool. However, it does not explicitly mention when not to use it or reference sibling alternatives like gtm_list_variables.

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