List enabled built-in variables

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

Annotations already declare read-only, idempotent, non-destructive, open-world behavior, so the safety profile is covered. The description adds useful behavioral context by explaining that the default workspace is looked up once and cached, and by clarifying the enabled-only scope.

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 compact and front-loaded with the core result, then moves efficiently through container formats, workspace id, and default behavior. Every sentence adds practical calling information without repetition.

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 read-only list tool with annotations and an output schema already available, the description is complete enough to invoke correctly. It covers both input parameters, the default workspace behavior, and the returned fields.

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 carry parameter meaning. It does: container accepts a public GTM id, linked destination id, or API path; workspace_id is numeric and may be omitted to use the cached Default Workspace.

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 states a specific verb and resource: listing built-in variables currently enabled in a workspace. It distinguishes built-in variables from the broader variable listing implied by sibling gtm_list_variables, and the example format reinforces the exact object being returned.

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?

Usage is implied by 'currently enabled in the workspace,' but there is no explicit guidance contrasting this with gtm_list_variables or gtm_enable_built_in_variables. The default-workspace behavior is helpful, but it is parameter guidance rather than when-to-use guidance.

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